The Milky Way’s galactic center is orbited by the Sυп, Earth, and the entire solar system at a blistering 140 miles per second.
Even at this great speed, though, oυr planetary пeighborhood still takes about 200 million years to make one complete orbit — a testament to the vast size of our home galaxy.
Scientists have warned that if Neptune's orbit is disrupted by a passing star by just 0.1 percent, the planets in our solar system might collide.
The research, published in the Monthly Notices of the Royal Astronomical Society, suggests that a "stellar flyby" - a relatively common occurrence in the universe - could be enough to cause planets to collide.
If Mercury and Jupiter's perihelion — the point at which the planets are closest to the Sun — occur at the same time, two scenarios are possible. Mercury's orbit could be disrupted, forcing it to leave the Solar System or collide with Venus, the Sun, or the Earth.
These changes will take millions of years to occur, but the researchers recreated the circumstance roughly three thousand times.
Over 2,000 of them ended with planets colliding or Uranus, Neptune, or Mercury being completely evacuated from the Solar System.
"The full role that stellar flybys play in the evolution of planetary systems is still being researched." "The consensus is that stellar flybys play an important role in planetary systems that form in a star cluster while the planetary system remains within the star cluster," says Garett Brown, a graduate student of computational physics at the University of Toronto's Department of Physical and Environmental Sciences (PES).
"Typically, this is the first 100 million years of planetary evolution." The occurrence rate of stellar flybys substantially falls after the star cluster evaporates, limiting their importance in the formation of planetary systems."
Furthermore, given that the Sun will undoubtedly expand and devour the Earth in five billion years, Brown believes that the potential of this disrupting our experience in the Solar System is "not a problem we need to be concerned about."
Astronomers in Chile used the powerful 570-megapixel Dark Energy Camera (DECam) to find an asteroid with the shortest orbital period of any known asteroid in the Solar System.
They did this just ten days ago. Every 113 days, the asteroid, which is about 1 kilometer across, comes as close to the Sun as 20 million kilometers (12 million miles or 0.13 au).
Asteroid 2021 PH27 has the shortest period and the shortest semi-major axis of any known asteroid in our Solar System. Only Mercury has a shorter period and a shorter semi-major axis. Since the asteroid is so close to the Sun, it feels the strongest effects of general relativity of any known object in the Solar System.
Scott S. Sheppard of the Carnegie Institution of Science found the asteroid 2021 PH27 by looking at data from the Dark Energy Camera (DECam) on the Vctor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. Ian Dell’antonio and Shenming Fu of Brown University took pictures of the asteroid in the evening sky on August 13, 2021, as it was getting dark.
Sheppard worked with Dell’antonio and Fu while using DECam to make observations for the Local Volume Complete Cluster Survey. This survey is looking at most of the large galaxy clusters in the nearby universe. They took a break from looking at some of the biggest objects millions of light-years away to look for asteroids much closer to Earth.
DECam is one of the best wide-field CCD imagers in the world. It was made for the DOE-funded Dark Energy Survey (DES), built and tested at the DOE’s Fermilab, and ran by the DOE and NSF from 2013 to 2019. At the moment, DECam is used for a wide range of science programs. The Community Science and Data Center is in charge of taking care of the DECam science archive (CSDC). The NOIRLab at NSF runs the CTIO and CSDC programs.
The best time to look for asteroids that are inside Earth’s orbit, in the direction of Mercury and Venus, is at twilight, just after sunset or just before sunrise. Any stargazer will tell you that Mercury and Venus never seem to get very far from the Sun in the sky and are always easiest to see near sunrise or sunset. Asteroids that orbit close to the Sun are the same.
After 2021 PH27 was found, David Tholen of the University of Hawai’i measured its position and figured out where it could be seen the next night. After that, on August 14, 2021, DECam and the Magellan Telescopes at the Las Campanas Observatory in Chile both looked at it again.
Then, on the evening of the 15th, Marco Micheli of the European Space Agency used the Las Cumbres Observatory network of 1- to 2-meter telescopes to look at it from CTIO in Chile and from South Africa. Other astronomers used DECam and Magellan to look at the newly found asteroid as well.
Sheppard says that even though astronomers’ telescope time is very valuable, the international nature of their work and their love of the unknown make them very willing to put their own science and observations on hold to follow up on new, interesting discoveries like this one.
Planets and asteroids move in oval-shaped orbits around the Sun. The widest part of the oval is called the semi-major axis, and it has a radius. The semi-major axis of 2021 PH27 is 70 million kilometers (43 million miles or 0.46 au), which gives it a 113-day orbital period on an elongated orbit that crosses both Mercury and Venus’ orbits.
It may have started out in the main Asteroid Belt between Mars and Jupiter but moved closer to the Sun because of gravitational disturbances from the inner planets. Its high orbital inclination of 32 degrees, on the other hand, suggests that it might be an extinct comet from the outer Solar System that was pulled into a closer, shorter-period orbit by one of the terrestrial planets as it passed by. As more observations are made of the asteroid, we will learn more about where it came from.
Its orbit is probably also unstable over long periods of time. In a few million years, it will probably either crash into Mercury, Venus, or the Sun, or it will be pushed out of the inner Solar System by the gravity of the inner planets.
Astronomers have a hard time finding asteroids in the inner solar system because the Sun’s light often hides them. When asteroids get so close to the Sun, they are put under a lot of stress, including thermal stress from the Sun’s heat and physical stress from the Sun’s gravitational tides. Some of the asteroids that are not as strong could break up because of these stresses.
“The number of asteroids that are close to Earth and Venus compared to those that are far away will tell us about their strength and make-up,” says Sheppard. If the number of asteroids in the same orbit as 2021 PH27 seems to be decreasing, it could tell astronomers how many near-Earth asteroids are loosely held together piles of rubble instead of solid chunks of rock. This could affect how we deal with asteroids that might be headed for Earth and how we try to stop them.
“Understanding the population of asteroids inside Earth’s orbit is important to finish the census of asteroids close to Earth,” says Sheppard. “Some of the most likely Earth-impacting asteroids may come close to Earth during the day, but they are hard to find in most surveys because they are done at night, when the Sun isn’t out.” He also says that since 2021 PH27 is so close to the Sun, “its surface temperature gets to almost 500 degrees C (around 900 degrees F) at closest approach, hot enough to melt lead.”
Because 2021 PH27 is so close to the Sun, its effects from general relativity are the strongest of any known Solar System object. This reveals itself as a slight angular deviation in the asteroid’s elliptical orbit over time, a movement called precession, which amounts to about one arcminute per century.
The asteroid is now moving behind the Sun, which we can see from where we are. This is called solar conjunction. It is expected to return to visibility from Earth early in 2022, when new observations will be able to determine its orbit in more detail, allowing the asteroid to get an official name.
The Ganymede Ocean is believed to contain more water than Europa's,” says Olivier Witasse, a project scientist working on ESA’s future Jupiter Icy Moon Explorer (JUICE).
“Six times more water in Ganymede’s ocean than in Earth's ocean, and three times more than Europa.” In March of 2020, NASA's Hubble Space Telescope revealed the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon --larger than Mercury and not much smaller than Mars.
Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search for life, as we know it. “This discovery marks a significant milestone, highlighting what only Hubble can accomplish,” said John Grunsfeld, now retired assistant administrator of NASA's Science Mission Directorate at NASA Headquarters. “In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.”
Ganymede is our solar system's largest moon and the only one with its own magnetic field. The magnetic field creates aurorae, which are ribbons of bright, hot electrified gas that circle the moon's north and south poles. Ganymede is surrounded by Jupiter's magnetic field due to its proximity. The aurorae on Ganymede vary as Jupiter's magnetic field changes, "rocking" back and forth.
Ganymede's fame is eclipsed by its sister ocean planet, Europa, which is scheduled for flybys by NASA's Europa Clipper mission in the 2020s, just as Saturn's moon, Dione, is perpetually overshadowed by Enceladus and Titan.
Ganymede's cycles of auroral activity on the surface, detected by the Hubble Space Telescope, reveal oscillations in the moon’s magnetic field best explained by the internal heat-generating tidal sloshing of a huge ocean hundreds of kilometers below the surface. JUICE will fly by the moons at distances between 1000 and 200 kilometers, orbiting Ganymede for nine months, with the latter four months at an altitude of about 500 km. While the oceans of Jupiter's moons are likely buried at significant depth below their icy crusts, radar will be able to help piece together clues as to their complex evolution.
For example, it will explore Europa's potentially active regions and be able to distinguish where the composition changes, such as if there are local, shallow reservoirs of water sandwiched between icy layers. It will be able to find 'deflected' subsurface layers, which will help to determine the tectonic history of Ganymede in particular.
Just over 300 light-years away is a star that's a lot like a very young version of our Sun, with multiple exoplanets orbiting it.
That's an interesting find in itself. But what makes the system truly dazzling is that it just became the first of its kind to be directly imaged, planets and all.
On the night of 16 February 2020, astronomers using the Very Large Telescope in Chile were able to obtain direct observations of two enormous exoplanets on extremely large orbits around the star named TYC 8998-760-1.
Directly imaging exoplanets is challenging, to say the least. They are very dim compared to their host stars, and very far away from us. Most of the over 4,000 exoplanets confirmed to date have only been detected via indirect means - such as faint, regular dips in the star's light as the exoplanet passes in front of it, or a slight wobble in the star's position due to the exoplanet's gravity.
Because these signals are easier to detect when the planet is very large and very close to the star, the majority of confirmed exoplanets are large and on close orbits. But exoplanets on very close orbits are difficult to image directly, because they tend to be vastly outshone by their host stars; and distantly orbiting planets in older systems are too cool for infrared detection.
To date, only a few tens of exoplanets have been directly imaged, and only two other multi-planet systems - both around stars very different from the Sun.
But last year, using direct imaging, a team of astronomers led by Alexander Bohn of Leiden University in the Netherlands found an unusual planet orbiting TYC 8998-760-1.
It was a gas giant around 14 times the mass of Jupiter, orbiting the star at a distance of around 160 astronomical units. To put that in perspective, Pluto orbits the Sun at an average distance of 39 astronomical units.
So Bohn and his colleagues decided to take a closer look, using the Very Large Telescope's exoplanet-imaging SPHERE instrument. They took several observations over the last year, and added them to data dating back to 2017.
When all the data were put together, they held a surprise. Clear and bright, there was the exoplanet they expected to see, TYC 8998-760-1 b. But, at a much greater distance of 320 astronomical units, the astronomers found another bright dot.
Careful analysis and comparison of images taken at different times revealed this wasn't a star or glitch, but a second, smaller exoplanet, clocking in at about six times the mass of Jupiter. It's been named TYC 8998-760-1 c.
"Our team has now been able to take the first image of two gas giant companions that are orbiting a young, solar analogue," said astronomer Maddalena Reggiani of KU Leuven in Belgium.
Such images aren't just wonderful achievements of science and technology, they can also help us to better understand planetary systems.
For one thing, TYC 8998-760-1 is young, only 16.7 million years old. Studying the exoplanets that orbit young Sun-like stars can give us valuable insight into the formation of planetary systems like our own.
The orbital distance the team detected is already quite interesting, because one model of planetary system formation posits that giant planets form at a distance before migrating inwards towards their host star.
For another, direct images of exoplanets can help us in the search for habitability. Detailed spectroscopic images - breaking down the spectrum of light reflected off an exoplanet - can reveal the presence of an atmosphere, and even the composition of that atmosphere. Photometry, or studying the exoplanets' brightness and variability thereof, can reveal information about cloud cover and abundance.
We're not quite at that stage yet, but future instruments, such as the James Webb Space Telescope, and the European Southern Observatory's ground based Extremely Large Telescope, ought to be sensitive enough to start making such detections.
And they might even be able to find smaller, closer planets in this system that SPHERE may have missed.
"The possibility that future instruments, such as those available on the Extremely Large Telescope, will be able to detect even lower-mass planets around this star marks an important milestone in understanding multi-planet systems, with potential implications for the history of our own Solar System," Bohn said.
The research has been published in The Astrophysical Journal Letters.
Yeti Dynamics, a YouTuber, developed a movie to demonstrate the size of the planets in our solar system by placing them in a familiar context: the Moon.
See for yourself by scrolling down!
VENUS has been chosen as the destination for two new NASA missions to investigate the planet's atmosphere and geological features, following the discovery of "enough water to support plentiful life" by NASA.
The space agency has announced it will send two robotic missions to the planet by the end of the decade. NASA administrator Bill Nelson said the probes — named Davinci+ and Veritas — will offer the "chance to investigate a planet we haven't been to in more than 30 years".
The missions to Earth’s closest planetary neighbour were picked following a peer-review process and will explore how the once habitable world became a “hot, hellish, unforgiving” planet.
It comes just months after astronomers from the UK controversially detected phosphine gas 30 miles up in Venus’ clouds, leading researchers to suggest it was a sign of alien life.
Scientists at NASA’s Goddard Institute for Space Studies (GISS) also previously found that Venus may have once had a shallow liquid-water ocean and a habitable surface temperature for up to two billion years.
The findings, published in the journal Geophysical Research Letters, were obtained with a model similar to the type used to predict future climate change on Earth.
Michael Way, a researcher at GISS and the paper’s lead author, said: “Many of the same tools we use to model climate change on Earth can be adapted to study climates on other planets, both past and present.
“These results show ancient Venus may have been a very different place than it is today.”
Scientists have long theorized that Venus was formed out of ingredients similar to Earth’s, but followed a different evolutionary path.
Measurements by NASA’s Pioneer mission to Venus in the Eighties first suggested Venus originally may have had an ocean, but its proximity to the Sun means it receives far more sunlight than Earth.
This led scientists to believe that the planet’s early ocean evaporated, water-vapour molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space.
With no water left on the surface, carbon dioxide built up in the atmosphere, causing a runaway greenhouse effect that created present conditions.
The GIIS team also suggested the 2016 data showed ancient Venus had more dry land overall than Earth, especially in the tropics.
A NASA press release added: “This type of surface appears ideal for making a planet habitable, there seems to have been enough water to support abundant life, with sufficient land to reduce the planet’s sensitivity to changes from incoming sunlight.”
Researchers simulated conditions of a hypothetical early Venus with an atmosphere similar to Earth’s, a day as long as Venus’ current day, and a shallow ocean consistent with early data from the Pioneer spacecraft.
Co-author Anthony Del Genio said: “In the GISS model’s simulation, Venus’ slow spin exposes its dayside to the Sun for almost two months at a time.
“This warms the surface and produces rain that creates a thick layer of clouds, which acts like an umbrella to shield the surface from much of the solar heating.
“The result is mean climate temperatures that are actually a few degrees cooler than Earth’s today.”
The last US probe to visit Venus was the Magellan orbiter in 1990.
However, other spacecraft - from Europe and Japan - have orbited the planet since then.
The Davinci+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) mission will measure the planet's atmosphere to gain insight into how it formed and evolved.
It will also aim to determine whether Venus ever had an ocean.
DAVINCI+ may also shed some light on observations of phosphine gas in Venus’s atmosphere.
If the spacecraft finds compelling evidence of the chemical phosphine, it may be a sign of life in the Venusian clouds.
The other mission, Veritas (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy), will map the planet's surface to understand its geological history and investigate how it developed so differently than Earth.
It will use a form of radar to chart surface elevations and discover whether volcanoes and earthquakes are active.
Updated version of the previous article.
Reference(s): MIT
All of the planets of the solar system are visible together in the night sky right now, providing stargazers with a "spectacular" show to end the year.
"These nights, we can see all the planets of our solar system at a glance, soon after sunset," Gianluca Masi, an astronomer with the Virtual Telescope Project told Newsweek. "It happens from time to time, but it is always a spectacular sight."
After December 24, the moon will also join the show, which can be seen from any location on Earth, assuming that skies are clear.
Starting from the south-western horizon, the naked eye planets will line-up in the following order: Venus, Mercury, Saturn, Jupiter and Mars. Mercury will be the hardest planet to see, being located in a bright part of the sky. While the planet may be visible to the naked eye, binoculars may help to locate it, as well as Venus.
You will also need binoculars to find Uranus, located between Mars and Jupiter, and Neptune—which is situated between Saturn and Jupiter.
"This way, we can see the entire planetary family," Masi said.
This "planetary parade" is not a regular occurrence, but is not as rare as you might expect—such an alignment takes place every one to two years or so, on average.
The last time all of the planets were visible in the sky simultaneously was June this year. During this show, the five naked eye planets were also lined up in the sky in the same sequential order that they physically orbit the sun—i.e. Mercury, Venus, Mars, Jupiter and Saturn. Such an alignment had not occurred for 18 years.
Uranus and Neptune were also visible with binoculars during this event but, they were not aligned in increasing order of distance from the sun.
The latest planetary parade is set to last until the end of the year, when Mercury will fade away, so you only have a few days to catch a glimpse of it.
If you would prefer to watch the event from the comfort of your own home, the Virtual Telescope Project will be providing a live stream showing the planets and the moon above the skyline of Rome.
The Virtual Telescope Project is a service provided by the Bellatrix Astronomical Observatory in Ceccano, Italy, managed by Masi, that operates and provides access to robotic, remotely-operated telescopes.
The Christmas live feed is schedule to begin at 4 p.m. UTC, or 11 a.m. Eastern Time, on December 28.
On November 5, 2018, NASA’s Voyager 2 joined its sister aircraft Voyager 1 beyond the heliosphere, ‘the protective bubble of particles and magnetic fields created by our Sun’.
Considered a ‘watershed moment in our exploration of space’, five new research papers have been published in the journal Nature Astronomy documenting what’s happened since the spacecraft crossed the boundary and raged against the dying of the light.
As per NASA’s Jet Propulsion Laboratory, Voyager 2’s findings will help ‘paint a picture of this cosmic shoreline, where the environment created by our Sun ends and the vast ocean of interstellar space begins’.
As told to IFLScience, NASA astrophysicist Jeffrey Hayes said:
This is a watershed moment in our exploration of space: we have for the first time left the confines of ‘home’ and are taking our very first tentative steps into the interstellar space – the Milky Way galaxy of which we are a part. That’s an amazing distance to come in only 62 years, since the launch of the first satellite. Who knows what the next 62 will bring?
Each of the research papers revolves around the spacecraft’s findings, compiled from its five operating instruments: a magnetic field sensor, two instruments to detect energetic particles in different energy ranges and two instruments for studying plasma (a gas composed of charged particles).
But just what is the heliosphere? Hayes offered an explanation, described it as a ‘somewhat porous boundary’.
Hayes added:
Inside is the space we live in, which is the very extended influence of the Sun and the solar wind that it generates, and outside is a region that is not under that same influence. Both Voyagers found this to be the case. The original model was that the solar wind would just gradually fade away until one was in the interstellar medium; clearly that’s not the case.
The heliopause acts as a somewhat porous boundary that only allows some particles to traverse it. Because we have only very recently passed through it – in 2012 with Voyager 1, and now with Voyager 2, there are still a lot of aspects of this we don’t understand.
Discussing further exploration possibilities, Hayes added:
While the Voyager 2 has yet to enter undisturbed interstellar space, the probes offer a groundbreaking illustration of how the ‘Sun interacts with the stuff that fills most of the space between stars in the Milky Way galaxy’.
Discussing further exploration possibilities, Hayes added:
In terms of space exploration, it means that we have only barely scratched the surface of what it means to be in interstellar space. All told, we have entered a new era of exploration that is posing as many new questions as it has answered our older ones.
Maybe it won’t be long until we send Matthew McConaughey through a wormhole.
Reference(s): IFLScience
Just over 300 light-years away is a star that's a lot like a very young version of our Sun, with multiple exoplanets orbiting it. That's an interesting find in itself. But what makes the system truly dazzling is that it just became the first of its kind to be directly imaged, planets and all.
On the night of 16 February 2020, astronomers using the Very Large Telescope in Chile were able to obtain direct observations of two enormous exoplanets on extremely large orbits around the star named TYC 8998-760-1.
Directly imaging exoplanets is challenging, to say the least. They are very dim compared to their host stars, and very far away from us. Most of the over 4,000 exoplanets confirmed to date have only been detected via indirect means - such as faint, regular dips in the star's light as the exoplanet passes in front of it, or a slight wobble in the star's position due to the exoplanet's gravity.
Because these signals are easier to detect when the planet is very large and very close to the star, the majority of confirmed exoplanets are large and on close orbits. But exoplanets on very close orbits are difficult to image directly, because they tend to be vastly outshone by their host stars; and distantly orbiting planets in older systems are too cool for infrared detection.
To date, only a few tens of exoplanets have been directly imaged, and only two other multi-planet systems - both around stars very different from the Sun.
But last year, using direct imaging, a team of astronomers led by Alexander Bohn of Leiden University in the Netherlands found an unusual planet orbiting TYC 8998-760-1.
It was a gas giant around 14 times the mass of Jupiter, orbiting the star at a distance of around 160 astronomical units. To put that in perspective, Pluto orbits the Sun at an average distance of 39 astronomical units.
So Bohn and his colleagues decided to take a closer look, using the Very Large Telescope's exoplanet-imaging SPHERE instrument. They took several observations over the last year, and added them to data dating back to 2017.
When all the data were put together, they held a surprise. Clear and bright, there was the exoplanet they expected to see, TYC 8998-760-1 b. But, at a much greater distance of 320 astronomical units, the astronomers found another bright dot.
Careful analysis and comparison of images taken at different times revealed this wasn't a star or glitch, but a second, smaller exoplanet, clocking in at about six times the mass of Jupiter. It's been named TYC 8998-760-1 c.
"Our team has now been able to take the first image of two gas giant companions that are orbiting a young, solar analogue," said astronomer Maddalena Reggiani of KU Leuven in Belgium.
Such images aren't just wonderful achievements of science and technology, they can also help us to better understand planetary systems.
For one thing, TYC 8998-760-1 is young, only 16.7 million years old. Studying the exoplanets that orbit young Sun-like stars can give us valuable insight into the formation of planetary systems like our own.
The orbital distance the team detected is already quite interesting, because one model of planetary system formation posits that giant planets form at a distance before migrating inwards towards their host star.
For another, direct images of exoplanets can help us in the search for habitability. Detailed spectroscopic images - breaking down the spectrum of light reflected off an exoplanet - can reveal the presence of an atmosphere, and even the composition of that atmosphere. Photometry, or studying the exoplanets' brightness and variability thereof, can reveal information about cloud cover and abundance.
We're not quite at that stage yet, but future instruments, such as the James Webb Space Telescope, and the European Southern Observatory's ground based Extremely Large Telescope, ought to be sensitive enough to start making such detections.
And they might even be able to find smaller, closer planets in this system that SPHERE may have missed.
"The possibility that future instruments, such as those available on the Extremely Large Telescope, will be able to detect even lower-mass planets around this star marks an important milestone in understanding multi-planet systems, with potential implications for the history of our own Solar System," Bohn said.
The research has been published in The Astrophysical Journal Letters.
A recent telescopic shot shows what will eventually happen to our own Milky Way.
A stunning telescope image reveals two galaxies that are entangled and will eventually merge into one galaxy millions of years from now, forecasting the Milky Way's doom.
The interacting spiral galaxies were discovered in the Virgo constellation, approximately 60 million light-years away, by the Gemini North telescope on Maunakea's summit.
The Butterfly galaxies, also known as NGC 4567 and NGC 4568, are two galaxies that are colliding owing to gravity right now.
After 500 million years, the two cosmic systems will merge to form a single elliptical galaxy.
At this early stage, the two galactic centres are 20,000 light-years apart, and each galaxy has retained its pinwheel configuration.
The image depicts the brilliant remnants of a supernova SN 2020fqv (callout box) discovered in 2020. This view from Hawaii's Gemini North telescope shows two interacting spiral galaxies, NGC 4568 (bottom) and NGC 4567 (top), as they collide and merge. In 500 million years, the galaxies will merge to form a single elliptical galaxy. International Gemini Observatory/NOIRLab/NSF/AURA are the photographers. T.A. Rector (University of Alaska Anchorage/NOIRLab), NSF's J. Miller (Gemini Observatory/NOIRLab), NSF's M. Zamani (NSF's NOIRLab), and D. de Martin (NSF's NOIRLab) processed the images.
As the galaxies become more linked, gravitational forces will induce a number of intense star formation events.
The architecture of the original galaxies will be altered and deformed.
They will dance in ever-shrinking circles around one another over time.
This complex looping dance will drag and stretch out long streamers of gas and stars, uniting the two galaxies into what appears to be a spherical.
This cosmic entanglement will destroy or disperse the gas and dust essential to begin star formation over millions of years, slowing and eventually stopping stellar formation.
Because of prior galaxy collisions and computer models, astronomers now have more evidence that spiral galaxies unite to form elliptical galaxies.
When the two are combined, the final structure will resemble Messier 89, an elliptical galaxy in the constellation Virgo.
After Messier 89 lost the majority of the gas required to make stars, very little star formation occurred.
The galaxy now contains older stars and ancient clusters.
The afterglow of a supernova, which was discovered for the first time in 2020, can also be seen as a bright point in one of the spiral arms of galaxy NGC 4568 in the new image.
Merger of the Milky Way
A comparable galactic merger will occur when the Milky Way galaxy collides with the Andromeda galaxy, our closest and most powerful galactic neighbour.
NASA researchers used Hubble data in 2012 to anticipate the likely date of a collision between the two spiral galaxies.
The event is expected to occur between 4 and 5 billion years from now.
According to research based on Hubble Space Telescope data released in 2020, the Andromeda galaxy's halo is currently pushing up against the Milky Way galaxy's halo.
Andromeda's halo, a huge envelope of gas, reaches out from the galaxy 1.3 million light-years out, nearly halfway to the Milky Way and up to 2 million light-years in other directions.
This neighbour is only 2.5 million light-years away, has the same size as our massive galaxy, and might hold a trillion stars.
From an astronomical standpoint, it may appear far away, but it pulls Andromeda so close that it may be seen in our October sky.
In the autumn, it may seem as a fuzzy cigar-shaped speck of light high in the sky.
Andromeda features a massive halo three times the width of the Big Dipper and dwarfs everything else in our sky, albeit it is invisible to the naked eye.
It's unlikely that our solar system will be killed when the Milky Way and Andromeda collide, but the Sun may be transported into a new area of the galaxy, opening up new vistas in Earth's night sky.
Just over 300 light-years away is a star that's a lot like a very young version of our Sun, with multiple exoplanets orbiting it. That's an interesting find in itself. But what makes the system truly dazzling is that it just became the first of its kind to be directly imaged, planets and all.
On the night of 16 February 2020, astronomers using the Very Large Telescope in Chile were able to obtain direct observations of two enormous exoplanets on extremely large orbits around the star named TYC 8998-760-1.
Directly imaging exoplanets is challenging, to say the least. They are very dim compared to their host stars, and very far away from us. Most of the over 4,000 exoplanets confirmed to date have only been detected via indirect means - such as faint, regular dips in the star's light as the exoplanet passes in front of it, or a slight wobble in the star's position due to the exoplanet's gravity.
Because these signals are easier to detect when the planet is very large and very close to the star, the majority of confirmed exoplanets are large and on close orbits. But exoplanets on very close orbits are difficult to image directly, because they tend to be vastly outshone by their host stars; and distantly orbiting planets in older systems are too cool for infrared detection.
To date, only a few tens of exoplanets have been directly imaged, and only two other multi-planet systems - both around stars very different from the Sun.
But last year, using direct imaging, a team of astronomers led by Alexander Bohn of Leiden University in the Netherlands found an unusual planet orbiting TYC 8998-760-1.
It was a gas giant around 14 times the mass of Jupiter, orbiting the star at a distance of around 160 astronomical units. To put that in perspective, Pluto orbits the Sun at an average distance of 39 astronomical units.
So Bohn and his colleagues decided to take a closer look, using the Very Large Telescope's exoplanet-imaging SPHERE instrument. They took several observations over the last year, and added them to data dating back to 2017.
When all the data were put together, they held a surprise. Clear and bright, there was the exoplanet they expected to see, TYC 8998-760-1 b. But, at a much greater distance of 320 astronomical units, the astronomers found another bright dot.
Careful analysis and comparison of images taken at different times revealed this wasn't a star or glitch, but a second, smaller exoplanet, clocking in at about six times the mass of Jupiter. It's been named TYC 8998-760-1 c.
"Our team has now been able to take the first image of two gas giant companions that are orbiting a young, solar analogue," said astronomer Maddalena Reggiani of KU Leuven in Belgium.
Such images aren't just wonderful achievements of science and technology, they can also help us to better understand planetary systems.
For one thing, TYC 8998-760-1 is young, only 16.7 million years old. Studying the exoplanets that orbit young Sun-like stars can give us valuable insight into the formation of planetary systems like our own.
The orbital distance the team detected is already quite interesting, because one model of planetary system formation posits that giant planets form at a distance before migrating inwards towards their host star.
For another, direct images of exoplanets can help us in the search for habitability. Detailed spectroscopic images - breaking down the spectrum of light reflected off an exoplanet - can reveal the presence of an atmosphere, and even the composition of that atmosphere. Photometry, or studying the exoplanets' brightness and variability thereof, can reveal information about cloud cover and abundance.
We're not quite at that stage yet, but future instruments, such as the James Webb Space Telescope, and the European Southern Observatory's ground based Extremely Large Telescope, ought to be sensitive enough to start making such detections.
And they might even be able to find smaller, closer planets in this system that SPHERE may have missed.
"The possibility that future instruments, such as those available on the Extremely Large Telescope, will be able to detect even lower-mass planets around this star marks an important milestone in understanding multi-planet systems, with potential implications for the history of our own Solar System," Bohn said.
The research has been published in The Astrophysical Journal Letters.
"The Ganymede Ocean is believed to contain more water than Europa's," says Olivier Witasse, a project scientist working on ESA’s future Jupiter Icy Moon Explorer (JUICE). “Six times more water in Ganymede’s ocean than in Earth's ocean, and three times more than Europa.” In March of 2020, NASA's Hubble Space Telescope revealed the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon --larger than Mercury and not much smaller than Mars.
Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search for life, as we know it. “This discovery marks a significant milestone, highlighting what only Hubble can accomplish,” said John Grunsfeld, now retired assistant administrator of NASA's Science Mission Directorate at NASA Headquarters. “In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.”
Ganymede is the largest moon in our solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter's magnetic field. When Jupiter's magnetic field changes, the aurorae on Ganymede also change, "rocking" back and forth.
Just as Saturn's moon, Dione is perennially overshadowed by Enceladus and Titan, Ganymede's fame is eclipsed by its sister ocean world, Europa, slated for flybys by NASA’s Europa Clipper mission in the 2020s.
Ganymede's cycles of auroral activity on the surface, detected by the Hubble Space Telescope, reveal oscillations in the moon’s magnetic field best explained by the internal heat-generating tidal sloshing of a huge ocean hundreds of kilometers below the surface. JUICE will fly by the moons at distances between 1000 and 200 kilometers, orbiting Ganymede for nine months, with the latter four months at an altitude of about 500 km. While the oceans of Jupiter's moons are likely buried at significant depth below their icy crusts, radar will be able to help piece together clues as to their complex evolution.
For example, it will explore Europa's potentially active regions and be able to distinguish where the composition changes, such as if there are local, shallow reservoirs of water sandwiched between icy layers. It will be able to find 'deflected' subsurface layers, which will help to determine the tectonic history of Ganymede in particular.
Yeti Dynamics, a YouTuber, developed a movie to demonstrate the size of the planets in our solar system by placing them in a familiar context: the Moon.
See for yourself by scrolling down!
The Ganymede Ocean is believed to contain more water than Europa's,” says Olivier Witasse, a project scientist working on ESA’s future Jupiter Icy Moon Explorer (JUICE). “Six times more water in Ganymede’s ocean than in Earth's ocean, and three times more than Europa.” In March of 2020, NASA's Hubble Space Telescope revealed the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon --larger than Mercury and not much smaller than Mars.
Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search for life, as we know it. “This discovery marks a significant milestone, highlighting what only Hubble can accomplish,” said John Grunsfeld, now retired assistant administrator of NASA's Science Mission Directorate at NASA Headquarters. “In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.”
Ganymede is our solar system's largest moon and the only one with its own magnetic field. The magnetic field creates aurorae, which are ribbons of bright, hot electrified gas that circle the moon's north and south poles. Ganymede is surrounded by Jupiter's magnetic field due to its proximity. The aurorae on Ganymede vary as Jupiter's magnetic field changes, "rocking" back and forth.
Ganymede's fame is eclipsed by its sister ocean planet, Europa, which is scheduled for flybys by NASA's Europa Clipper mission in the 2020s, just as Saturn's moon, Dione, is perpetually overshadowed by Enceladus and Titan.
Ganymede's cycles of auroral activity on the surface, detected by the Hubble Space Telescope, reveal oscillations in the moon’s magnetic field best explained by the internal heat-generating tidal sloshing of a huge ocean hundreds of kilometers below the surface. JUICE will fly by the moons at distances between 1000 and 200 kilometers, orbiting Ganymede for nine months, with the latter four months at an altitude of about 500 km. While the oceans of Jupiter's moons are likely buried at significant depth below their icy crusts, radar will be able to help piece together clues as to their complex evolution.
For example, it will explore Europa's potentially active regions and be able to distinguish where the composition changes, such as if there are local, shallow reservoirs of water sandwiched between icy layers. It will be able to find 'deflected' subsurface layers, which will help to determine the tectonic history of Ganymede in particular.
Scientists have warned that if Neptune's orbit is disrupted by a passing star by just 0.1 percent, the planets in our solar system might collide.
The research, published in the Monthly Notices of the Royal Astronomical Society, suggests that a "stellar flyby" - a relatively common occurrence in the universe - could be enough to cause planets to collide.
If Mercury and Jupiter's perihelion — the point at which the planets are closest to the Sun — occur at the same time, two scenarios are possible. Mercury's orbit could be disrupted, forcing it to leave the Solar System or collide with Venus, the Sun, or the Earth.
These changes will take millions of years to occur, but the researchers recreated the circumstance roughly three thousand times.
Over 2,000 of them ended with planets colliding or Uranus, Neptune, or Mercury being completely evacuated from the Solar System.
"The full role that stellar flybys play in the evolution of planetary systems is still being researched." "The consensus is that stellar flybys play an important role in planetary systems that form in a star cluster while the planetary system remains within the star cluster," says Garett Brown, a graduate student of computational physics at the University of Toronto's Department of Physical and Environmental Sciences (PES).
"Typically, this is the first 100 million years of planetary evolution." The occurrence rate of stellar flybys substantially falls after the star cluster evaporates, limiting their importance in the formation of planetary systems."
Furthermore, given that the Sun will undoubtedly expand and devour the Earth in five billion years, Brown believes that the potential of this disrupting our experience in the Solar System is "not a problem we need to be concerned about."
VENUS has been chosen as the destination for two new NASA missions to investigate the planet's atmosphere and geological features, following the discovery of "enough water to support plentiful life" by NASA.
The space agency has announced it will send two robotic missions to the planet by the end of the decade. NASA administrator Bill Nelson said the probes — named Davinci+ and Veritas — will offer the "chance to investigate a planet we haven't been to in more than 30 years". The missions to Earth’s closest planetary neighbour were picked following a peer-review process and will explore how the once habitable world became a “hot, hellish, unforgiving” planet.
It comes just months after astronomers from the UK controversially detected phosphine gas 30 miles up in Venus’ clouds, leading researchers to suggest it was a sign of alien life.
Scientists at NASA’s Goddard Institute for Space Studies (GISS) also previously found that Venus may have once had a shallow liquid-water ocean and a habitable surface temperature for up to two billion years.
The findings, published in the journal Geophysical Research Letters, were obtained with a model similar to the type used to predict future climate change on Earth.
Michael Way, a researcher at GISS and the paper’s lead author, said: “Many of the same tools we use to model climate change on Earth can be adapted to study climates on other planets, both past and present.
“These results show ancient Venus may have been a very different place than it is today.”
Scientists have long theorized that Venus was formed out of ingredients similar to Earth’s, but followed a different evolutionary path.
Measurements by NASA’s Pioneer mission to Venus in the Eighties first suggested Venus originally may have had an ocean, but its proximity to the Sun means it receives far more sunlight than Earth.
This led scientists to believe that the planet’s early ocean evaporated, water-vapour molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space.
With no water left on the surface, carbon dioxide built up in the atmosphere, causing a runaway greenhouse effect that created present conditions.
The GIIS team also suggested the 2016 data showed ancient Venus had more dry land overall than Earth, especially in the tropics.
A NASA press release added: “This type of surface appears ideal for making a planet habitable, there seems to have been enough water to support abundant life, with sufficient land to reduce the planet’s sensitivity to changes from incoming sunlight.”
Researchers simulated conditions of a hypothetical early Venus with an atmosphere similar to Earth’s, a day as long as Venus’ current day, and a shallow ocean consistent with early data from the Pioneer spacecraft.
Co-author Anthony Del Genio said: “In the GISS model’s simulation, Venus’ slow spin exposes its dayside to the Sun for almost two months at a time.
“This warms the surface and produces rain that creates a thick layer of clouds, which acts like an umbrella to shield the surface from much of the solar heating.
“The result is mean climate temperatures that are actually a few degrees cooler than Earth’s today.”
The last US probe to visit Venus was the Magellan orbiter in 1990.
However, other spacecraft - from Europe and Japan - have orbited the planet since then.
The Davinci+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) mission will measure the planet's atmosphere to gain insight into how it formed and evolved.
It will also aim to determine whether Venus ever had an ocean.
DAVINCI+ may also shed some light on observations of phosphine gas in Venus’s atmosphere.
If the spacecraft finds compelling evidence of the chemical phosphine, it may be a sign of life in the Venusian clouds.
The other mission, Veritas (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy), will map the planet's surface to understand its geological history and investigate how it developed so differently than Earth.
It will use a form of radar to chart surface elevations and discover whether volcanoes and earthquakes are active.
Updated version of the previous article.
Reference(s): MIT