Tag Archives: Planets

Science

New Technique Used to Spot Possible Super-Earth in Alpha Centauri’s Habitable Zone

Leave a comment

Astronomers using a new technique may have not only found a super-Earth at a neighbouring star, but they may also have directly imaged it. And it could be nice and cozy in the habitable zone around Alpha Centauri.

 

It’s much easier to see giant planets than Earth-size planets. No matter which detection method is being used, larger planets are simply a larger needle in the cosmic haystack. But overall, astronomers are very interested in planets that are similar to Earth. And finding them is much more difficult.

We thought we’d have to wait for the ultra-powerful telescopes currently being built before we could directly image exoplanets.

Facilities like the Giant Magellan Telescope and the European Extremely Large Telescope will bring enormous observing power to bear on the task of exoplanet imaging.

But a team of researchers have developed a new technique that might do the job. They say they’ve imaged a possible sub-Neptune/super-Earth-sized planet orbiting one of our nearest neighbours, Alpha Centauri A.

The team presented their observations in an article in Nature Communications titled “Imaging low-mass planets within the habitable zone of α Centauri.” The lead author is Kevin Wagner, an astronomer and Sagan Fellow at the University of Arizona.

While astronomers have found low-mass exoplanets before, they’ve never sensed their light. They’ve watched as the planets revealed themselves by tugging on their stars. And they’ve watched as the light from the stars that host these planets dips when the planet passes in front of the star.

 

But they’ve never directly imaged one. Until now, maybe.

This new detection method comes down to the infrared. One of the challenges in imaging Earth-sized exoplanets in infrared is to discern the light coming from an exoplanet when that light is washed out by all of the background infrared radiation from the star.

Astronomers can search for exoplanets in wavelengths where the background infrared is diminished, but in those same wavelengths, temperate Earth-like planets are faint.

One method is to look in the near-infrared (NIR) part of the spectrum. In NIR, the thermal glow of the planet is not so washed out by the star. But the starlight is still blinding, and millions of times brighter than the planet. So just looking in the NIR is not a total solution.

The solution may be the NEAR (New Earths in the AlphaCen Region) instrument used in this research. NEAR is mounted on the ESO (European Southern Observatory’s) Very Large Telescope (VLT) in Chile. It works with the VISIR instrument, also on the VLT. The group behind NEAR is the Breakthrough Watch, part of Yuri Milner’s Breakthrough Initiatives.

 

The NEAR instrument not only observes in the desirable part of the infrared spectrum, but it also employs a coronagraph.

The Breakthrough group thought that the NEAR instrument used on an 8-meter ground-based telescope would allow for better observations of the Alpha Centauri system and its planets.

So they built the instrument in collaboration with the ESO and installed it on the Very Large Telescope.

This new finding came as a result of 100 hours of cumulative observations with NEAR and the VLT.

“These results,” the authors write, “demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes.”

The 100-hour commissioning run was meant to demonstrate the power of the instrument.

The team says that based on about 80 percent of the best images from that run, the NEAR instrument is an order of magnitude better than other methods for observing “…warm sub-Neptune-sized planets throughout much of the habitable zone of α Centauri A.”

They also, possibly, found a planet. “We also discuss a possible exoplanet or exozodiacal disk detection around? Centauri A,” they write. “However, an instrumental artifact of unknown origin cannot be ruled out.”

 

This isn’t the first time astronomers have found exoplanets in the Alpha Centauri system.

There are a couple of confirmed planets in the system, and there are also other candidates.

But none of them have been directly imaged like this new potential planet, which has the placeholder name C1, and is the first potential detection around the M-dwarf in the system, Proxima Centauri.

Follow-up observations will have to confirm or cancel the discovery.

It’s exciting to think that a warm-Neptune class exoplanet could be orbiting a Sun-like star in our nearest neighbouring star system. One of the Breakthrough Initiatives goals is to send lightsail spacecraft to the Alpha Centauri system and give us a closer look.

But that prospect is out of reach for now. And in some ways, this discovery isn’t so much about the planet, but about the technology developed to detect it.

The large majority of discovered exoplanets are gigantic planets similar in mass to Jupiter, Saturn, and Neptune. They’re the easiest to find. But as humans from Earth, we’re predominantly interested in planets like our own.

Earth-like planets in a star’s habitable zone get us excited about prospects for life on another planet. But they can also tell us a lot about our own Solar System, and how solar systems in general form and evolve.

If C1 does turn out to be a planet, then the Breakthrough group has succeeded in a vital endeavour. They’re the first to detect an Earth-like planet by direct imaging.

Not only that, but they did it with an 8-meter, ground-based telescope and an instrument specifically designed and developed to detect these types of planets in the Alpha Centauri system.

The authors are confident that NEAR can perform well, even in comparison to much larger telescopes. The conclusion of the paper contains a description of the overall sensitivity of the instrument. Then they write that “This would in principle be sufficient to detect an Earth-analog planet around α Centauri A (~20 µJy) in just a few hours, which is consistent with expectations for the ELTs.”

The E-ELT will have a 39-meter primary mirror. One of its capabilities and design goals is to image exoplanets, especially smaller, Earth-size ones, directly.

Of course, the E-ELT will be an enormously powerful telescope that will undoubtedly fuel scientific discovery for a long time, not just in exoplanet imaging but in a variety of other ways.

And other gigantic ground-based telescopes will change the exoplanet imaging game, too.

What took hours for NEAR to see may take only minutes for the E-ELT, the Thirty Meter Telescope, or the Giant Magellan Telescope to see.

NEAR can’t compete with those telescopes and was never meant to.

But if these results are confirmed, then NEAR has succeeded where nobody else has, and for a fraction of the price of a new telescope.

Either way, what NEAR has accomplished likely represents the future of exoplanet research. Rather than broad-based surveys like Kepler and TESS, scientists will soon be able to focus on individual planets.

This article was originally published by Universe Today. Read the original article.

 

Read original article here

Science

Planetoid ‘Farfarout’ is the Solar System’s most distant known object

Leave a comment

The most distant known object in our Solar System has been identified by astronomers.

It’s been given the fitting nickname “Farfarout” and is classified as a ‘planetoid’.

This means it’s too small to be considered a planet or a dwarf planet but is still a mass that orbits our Sun.

There was once a time when astronomers thought Pluto was the most distant object orbiting the Sun.

Advancements in technology mean scientists now have a much deeper gaze into the space.

Scientifically known as 2018 AG37, Farfarout is around 12.4 billion miles from the Sun.

In comparison, Earth is only around 93 million miles away.

Dwarf planet Pluto is about 3.7 billion miles away.

However, Farfarout occasionally moves closer to the Sun and Earth on it’s 1,000 year orbit path.

It’s orbit shape means there’s a point every 1,000 years when Farfarout becomes closer to the Sun than both Neptune and Pluto.

This GIF shows the motion of Farfarout, highlighted, between Jan. 15 and Jan. 16 2018, as seen with the Subaru telescope.
Scott S. Sheppard/Carnegie Institution for Science

So it might be the furthest object in our Solar System for now but it won’t always keep that title.

There’s a dwarf planet called Goblin which is currently closer to the Sun than Farfarout but has the potential to move much further away on its orbital path.

Research David Tholen from the University of Hawai’i said: “Farfarout’s orbital dynamics can help us understand how Neptune formed and evolved, as Farfarout was likely thrown into the outer Solar System by getting too close to Neptune in the distant past.

“Farfarout will likely interact with Neptune again since their orbits continue to intersect.”

Farfarout’s 1,000 year orbit time meant the researchers had to study it for years to determine its trajectory.

It was actually discovered back in 2018 but its exact distance hadn’t been determined until recently.

Astronomers think it’s around 250 miles wide.

It will remain under observation and eventually be given an official name that’s more serious than Farfarout and less data specific than 2018 AG37.

An artist’s conception of “Farfarout” on the outer reaches of our Solar System.
NOIRLab/NSF/AURA/J. da Silva

Read original article here

Science

Chinese spacecraft enters Mars’ orbit, joining Arab ship

Leave a comment

BEIJING (AP) — A Chinese spacecraft went into orbit around Mars on Wednesday on an expedition to land a rover on the surface and scout for signs of ancient life, authorities announced in a landmark step in the country’s most ambitious deep-space mission yet.

The arrival of Tianwen-1 after a journey of seven months and nearly 300 million miles (475 million kilometers) is part of an unusual burst of activity at Mars: A spacecraft from the United Arab Emirates swung into orbit around the red planet on Tuesday, and a U.S. rover is set to arrive next week.

China’s space agency said the five-ton combination orbiter and rover fired its engine to reduce its speed, allowing it to be captured by Mars’ gravity.

“Entering orbit has been successful … making it our country’s first artificial Mars satellite,” the agency announced.

The mission is bold even for a space program that has racked up a steady stream of achievements and brought prestige to China’s ruling Communist Party.

If all goes as planned, the rover will separate from the spacecraft in a few months and touch down safely on Mars, making China only the second nation to pull off such a feat. The rover, a solar-powered vehicle about the size of a golf cart, will collect data on underground water and look for evidence that the planet may have once harbored microscopic life.

Tianwen, the title of an ancient poem, means “Quest for Heavenly Truth.”

Landing a spacecraft on Mars is notoriously difficult. Smashed Russian and European spacecraft litter the landscape along with a failed U.S. lander. About a dozen orbiters missed the mark. In 2011, a Mars-bound Chinese orbiter that was part of a Russian mission didn’t make it out of Earth orbit.

Only the U.S. has successfully touched down on Mars — eight times, beginning with two Viking missions in the 1970s. An American lander and rover are in operation today.

China’s attempt will involve a parachute, rocket firings and airbags. Its proposed landing site is a vast, rock-strewn plain called Utopia Planitia, where the U.S. Viking 2 lander touched down in 1976.

Before the arrival this week of the Chinese spacecraft and the UAE’s orbiter, six other spacecraft were already operating around Mars: three U.S., two European and one Indian.

All three of the latest missions were launched in July to take advantage of the close alignment between Earth and Mars that happens only once every two years.

A NASA rover called Perseverance is aiming for a Feb. 18 landing. It, too, will search for signs of ancient microscopic life, collecting rocks that will be returned to Earth in about a decade.

China’s secretive, military-linked space program has racked up a series of achievements. In December, it brought moon rocks back to Earth for the first time since the 1970s. China was also the first country to land a spacecraft on the little-explored far side of the moon in 2019.

China is also building a permanent space station and planning a crewed lunar mission and a possible permanent research base on the moon, though no dates have yet been proposed.

While most contacts with NASA are blocked by Congress and China is not a participant in the International Space Station, it has increasingly cooperated with the European Space Agency and countries such as Argentina, France and Austria. Early on, China cooperated with the Soviet Union and then Russia.

Read original article here

Science

The ESA’s Solar Orbiter snaps unreal images of four planets at the same time

Leave a comment

We truly live on the cusp of a remarkable new era of space exploration, with SpaceX rockets rumbling almost every month and international probes spread out around the Milky Way capturing wondrous images of asteroids, comets, planets, moons, and our own shining Sun.

With all the activity and media coverage of these spacecraft and probes, it’s easy to become complacent or apathetic towards the data and photos their missions are delivering back to Earth. So let’s pause for a moment and gaze into the heavens at these dazzling new pics from NASA/ESA’s Solar Orbiter as it traverses our solar system studying our home star.

The new video footage below, pieced together with a series of photos, shows an incredibly rare cosmic tableaux of Earth, Mars, and Venus, with the faint light of Uranus also winking at us from beyond.

Video of Solar Orbiter snaps Venus, Earth and Mars

These inspiring images were obtained on November 18, 2020 by the SoloHI camera installed aboard Solar Orbiter. Venus (left), Earth (middle), and Mars (right) are clearly visible in the foreground, with a tapestry of bright stars in the background, all captured while the spacecraft loops around the Sun. Eagle-eyed astronomers also noted that Uranus shares the stage near the bottom edge.

“Solar Orbiter is the most complex scientific laboratory ever to have been built to study the Sun and the solar wind, taking images of our star from closer than any spacecraft before,” ESA researchers noted. “The Solar Orbiter Heliospheric Imager (SoloHI) is one of the six remote-sensing instruments onboard the mission. During the cruise phase, these are still being calibrated during specific periods, but are switched off otherwise.”

Venus, Earth, and Mars shift slightly in the SoloHI instrument’s field-of-view. Venus is the brightest object seen, hovering roughly 30 million miles away from the Solar Orbiter. When the shots were taken that day, the distance to Earth was 156 million miles and 206 million miles to Mars. Far off Uranus is a mere dot located beside the official time code.

“At the moment of the recording, Solar Orbiter was on its way to Venus for its first gravity assist flyby, which happened on December 27,” ESA scientists explained. “Venus and Earth flybys will bring the spacecraft closer to the Sun and tilt its orbit in order to observe our star from different perspectives.”

Read original article here

Science

Intriguing ‘Life’ Signal on Venus Was Plain Old Sulphur Dioxide, New Research Suggests

Leave a comment

The night side of Venus as seen in thermal infrared.
Image: JAXA/ISAS/DARTS/Damia Bouic

Scientists stunned the world last year by claiming to have discovered traces of phosphine in the Venusian clouds. New research suggests this gas—which, excitingly, is produced by microbes—was not actually responsible for the signal they detected. Instead, it was likely sulfur dioxide, a not-so-thrilling chemical.

Extraordinary research published in Nature last September is being challenged by a paper set to be published in The Astrophysical Journal, a preprint of which is currently available at the arXiv. This is not the first paper to critique the apparent discovery of phosphine on Venus, and it’s probably not going to be the last.

That phosphine might be present on Venus was a revelation that blew our minds, and that’s because living organisms are one of the only known sources of the stinky gas. The team responsible for the apparent discovery, led by astronomer Jane Greaves from Cardiff University, found the evidence in spectral signals collected by two radio dishes: the James Clerk Maxwell Telescope (JCMT) and the Atacama Large Millimeter/submillimeter Array (ALMA). Spectral lines at certain wavelengths indicate the presence of specific chemicals, and in this case they implied the presence of phosphine in the Venusian cloud layer.

The authors of the Nature study were not claiming that life exists on Venus. Rather, they were asking the scientific community to explain their rather bizarre observation. Indeed, it was an exceptional claim, as it implied that Venus—one of the most inhospitable planets in the solar system—might actually be habitable, with microscopic organisms floating through the clouds.

Alas, this doesn’t appear to be the case.

“Instead of phosphine in the clouds of Venus, the data are consistent with an alternative hypothesis: They were detecting sulfur dioxide,” Victoria Meadows, a co-author of the new study and an astronomy professor at the University of Washington, explained in a statement. “Sulfur dioxide is the third-most-common chemical compound in Venus’ atmosphere, and it is not considered a sign of life.”

G/O Media may get a commission

Meadows, along with researchers from NASA, the Georgia Institute of Technology, and the University of California, Riverside, reached this conclusion by modeling conditions inside the Venusian atmosphere, which they did to re-interpret the radio data gathered by the original team.

“This is what’s known as a radiative transfer model, and it incorporates data from several decades’ worth of observations of Venus from multiple sources, including observatories here on Earth and spacecraft missions like Venus Express,” explained Andrew Lincowski, a researcher with the UW Department of Astronomy and the lead author of the paper, in the statement.

Equipped with the model, the researchers simulated spectral lines produced by phosphine and sulphur at multiple atmospheric altitudes on Venus, as well as how those signatures were received by ALMA and JCMT. Results showed that the shape of the signal, detected at 266.94 gigahertz, likely came from the Venusian mesosphere—an extreme height where sulphur dioxide can exist but phosphine cannot owing to the harsh conditions there, according to research. In fact, so extreme is this environment that phosphine wouldn’t last for more than a few seconds.

As the authors argue, the original researchers understated the amount of sulphur dioxide in the Venusian atmosphere and instead attributed the 266.94 gigahertz signal to phosphine (both phosphine and sulphur dioxide absorb radio waves around this frequency). This happened, according to the researchers, due to an “undesirable side-effect” known as spectral line dilution, study co-author and NASA JPL scientist Alex Akins explained in the statement.

“They inferred a low detection of sulfur dioxide because of [an] artificially weak signal from ALMA,” added Lincowski. “But our modeling suggests that the line-diluted ALMA data would have still been consistent with typical or even large amounts of Venus sulfur dioxide, which could fully explain the observed JCMT signal.”

This new result could prove devastating for the Nature paper, and it’ll be interesting to hear how the authors respond to this latest critique. That said, some scientists believe the writing is already on the wall, or more accurately, the trash bin.

“Already quickly after publication of the original work, we and others have put strong doubts on their analysis,” wrote Ignas Snellen, a professor at Leiden University, in an email. “Now, I personally think that this is the final nail in the coffin of the phosphine hypothesis. Of course, one can never prove that Venus is completely phosphine-free, but at least there is now no remaining evidence to suggest otherwise. I am sure that others will keep on looking though.”

Back in December, Snellen and his colleagues challenged the Nature study, arguing that the method used by the Greaves team resulted in a “spurious” high signal-to-noise ratio and that “no statistical evidence” exists for phosphine on Venus.

The apparent absence of phosphine on Venus, and thus the absence of any hints of microbial life, is far less interesting than the opposite, but that’s how it goes sometimes. Science makes no claims or promises about the interestingness of all things, and we, as defenders of the scientific method, must come to accept our unfolding universe as we find it.

Read original article here

Science

A string of planets in our solar system sparkles in photos from 3 different sun probes

Leave a comment

NASA’s Parker Solar Probe spotted six different planets on June 7, 2020, with the sun out of frame to the left. (Image credit: NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher)

Turns out sungazing is not the only thing NASA’s solar spacecraft do.

Three missions that focus on the activities of our nearest star — Parker Solar Probe, the Solar and Terrestrial Relations Observatory (STEREO) and Solar Orbiter (a partnership with the European Space Agency) — have captured some incredible images showing several worlds in our solar system.

These spacecraft are flying in different areas of our neighborhood on a quest to understand solar phenomena such as the extreme heat of the sun’s outer atmosphere, the distribution of dust in our solar system or the production of the solar wind — the constant stream of particles coming from our sun. But each spacecraft caught amazing views of planets that NASA’s Goddard Space Flight Center in Maryland shared in a recent press release. 

Solar Orbiter 

This joint mission with ESA will eventually leave the plane of the solar system to study the sun’s poles. The spacecraft first transmitted test images in July 2020, about five months after its launch. 

On Nov. 18 came a particularly stunning image, when Solar Orbiter captured three planets in the same view. From left to right, you can see Venus (which appears exceedingly bright as the sun bounces off the planet’s clouds), Uranus, Earth and Mars. The sun is just out of the image view on the right-hand side of the frame. 

Solar Orbiter was roughly 155.7 million miles (250.6 million kilometers) away from Earth when the data was transmitted, which is a little less than twice the distance from the sun to Earth, or two astronomical units (AU). A single AU is roughly 93 million miles (150 million km). 

Parker Solar Probe 

NASA’s Parker Solar Probe will fly closer to the sun than any other spacecraft to date as it tries to capture the “origin story” of the solar wind. In this incredible wide-field image of June 7, 2020 (days before a close approach to the sun), it imaged six of our solar system’s planets. 

From left to right, they are Mars, Saturn, Jupiter, Venus, Earth and Mercury. The spacecraft was roughly one AU from Earth at imaging time, at 98.3 million miles (158 million kilometers).

STEREO 

NASA’s STEREO spacecraft spotted six planets on June 7, 2020. (Image credit: NASA/STEREO/HI)

The single operational STEREO spacecraft — one of a pair that circled the sun behind and ahead of Earth in our planet’s approximate orbit starting in 2014 — also gazed at the planets on June 7, 2020. In this image you can see the same six planets as Parker on the same date, but from a different vantage point in the solar system. 

From left to right appear Mercury, Mars, Venus, Earth, Saturn and Jupiter. The dark columns in the image are due to the detector being saturated, which is a combination of the long exposure time with the relative brightness of the planets compared to the background stars, according to NASA. 

STEREO’s normal mission is to study the sun’s outer atmosphere, or corona, along with the solar wind, to improve solar weather predictions.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook. 



Read original article here

Science

Enigmatic Star System Has 5 Planets Locked in Perfect Harmony

Leave a comment

Artist’s impression of the TOI-178 system.
Image: ESO

A unique planetary system located 200 light-years from Earth hosts five exoplanets with orbits locked together in a repeating pattern, despite their very different sizes and densities. The discovery is challenging astronomers’ notions of the kinds of planetary systems that can exist and how they form.

Five of six exoplanets in orbit around the star TOI-178 are in an 18:9:6:4:3 orbital resonance with each other, according to new research published today in Astronomy & Astrophysics. So for every 18 orbits made by the innermost of these five exoplanets, the next planet along the chain will complete nine orbits during the exact same period. The third will complete six orbits, and so on. The video below offers a demonstration of the process in action.

The innermost of the six exoplanets (shown with a blue orbital path) is not in resonance with the others, though it might have been in the past. In the animation above, rhythmic patterns are represented by red pulses and a chime sound (in the pentatonic scale), which get triggered when each exoplanet completes either a full orbit or a half orbit. As the video shows, two or more exoplanets trigger the chime quite often, the result of them being in orbital resonance. The new study was led by Adrien Leleu, CHEOPS fellow at the University of Geneva.

When Leleu, a dynamicist (an expert in celestial mechanics) and his colleagues first observed the TOI-178 system, they thought they saw two planets orbiting around the host star in the same orbit, but this result was inconclusive. The scientists decided to make follow-up observations using the European Space Agency’s CHEOPS satellite and the ground-based ESPRESSO instrument on the European Southern Observatory’s Very Large Telescope, in addition to the Next Generation Transit Survey and SPECULOOS projects, both in Chile. All these instruments allowed the team to detect the six exoplanets and characterize their orbits, which they did using the transit method (looking at the dimming of the host star when a planet passes in front) and by measuring the wobble of the host star.

All six exoplanets are in close proximity to the central star, with the nearest planet taking around two days to make a complete orbit and the most distant orbiting in around 20 days. None are inside the habitable zone, the Goldilocks region around a star where liquid water (and thus life) would be possible. Five of the six exoplanets are locked in perfect resonance, such that some planets come into alignment every few orbits. The 18:9:6:4:3 chain is among the longest ever discovered.

G/O Media may get a commission

Orbital resonance happens when orbiting bodies exert a periodic gravitational influence on each other. In our solar system, Jupiter’s moons Io, Europa, and Ganymede are in a 4:2:1 resonance.

The TOI-178 is interesting for a number of reasons, with the orbital resonance a sign of prolonged stability.

“From our understanding of planet formations, chain of resonances often occurs in the earliest phases of planetary system formation, when the star is still surrounded by a gaseous disc,” Leleu explained in an email. “However during the billions of years that follow the formation, many things can happen and most systems get out of the resonances. It can happen slowly, due to [gravitational] tidal effects for example, or violently, due to instability and planet collision/ejection.”

Only five other star systems have resonant chains involving four or more planets, “which is not a lot,” he added. Astronomers consider these planetary systems to be rare and quite young.

“What is unique to TOI-178 is not only this orbital configuration, but also the planets’ composition,” said Leleu. This consequently presents a challenge to our understanding of how planets form and evolve.

Indeed, the planets are between one and three times the size of Earth but have masses ranging from 1.5 to 30 times the mass of Earth. So while their orbital configurations are neat and tidy, their compositions are not. For example, one planet is a super-Earth, but its immediate neighbor is a low-density ice giant similar to Neptune. We don’t see that sort of thing around here.

According to Leleu, theory suggests that the planets should have lower density the farther they are from their star. But that’s not the case here. “In TOI-178, it’s only true for the two inner planets that are rocky, but then the third planet from the star has a very low density, then planet 4 and 5 are more dense, and then planet 6 is once again more fluffy,” he said.

Astronomers will now have to figure out how the system formed, including whether some of the planets formed farther out and slowly drifted inward.

Interestingly, TOI-178 could host other, more distant planets, but they just haven’t been detected. Looking ahead, ESO’s upcoming Extremely Large Telescope, which should become operational later this decade, might be able to to learn more about this odd star system. 

Read original article here