The first asteroid we’ve seen from outside our Solar System is totally bizarre



The first asteroid we’ve seen from outside our Solar System is totally bizarre


The first distant visitor we’ve ever observed

An artist’s impression of the first interstellar asteroid, `Oumuamua.
 European Southern Observatory

Astronomers have confirmed that an object that recently passed by our planet is from outside our Solar System — the first interstellar asteroid that’s ever been observed. And it doesn’t look like any object we’ve ever seen in our cosmic neighborhood before.

Follow-up observations, detailed today in Nature, have found that the asteroid is dark and reddish, similar to the objects in the outer Solar System. It doesn’t have any gas or dust surrounding it like comets do, and it’s stretched long and skinny, looking a bit like an oddly shaped pen. It’s thought to be about a quarter-mile long, and about 10 times longer than it is wide. That makes it unlike any asteroids seen in our Solar System, none of which are so elongated.

Astronomers also think this object — nicknamed `Oumuamua, Hawaiian for “a messenger from afar arriving first”— traveled for millions of years before stumbling upon our Solar System. It seems to have come from the direction of the constellation Lyra, but the asteroid’s exact origin is still unknown. More answers might come soon, as NASA’s Hubble Space Telescope is observing `Oumuamua this week. “Our plan is to look at it through the end of the year, so we can get the very best pass possible and figure out where it came from,” Karen Meech, lead author of the study at the University of Hawaii’s Institute of Astronomy, tells The Verge.

`Oumuamua was first spotted on October 19th by astronomers working on the Pan STARRS telescope in Hawaii. The telescope is used to scan the sky for objects orbiting near Earth, looking for any that might pose a threat to our planet. But one of the rocks in the latest observations looked as if it might not belong in our neck of the Universe.

The team at Pan STARRS continued observing the object over the next couple of days. Based on their measurements, they were fairly certain that they were watching the first ever interstellar asteroid. Up until then, such a distant visitor had never been seen before, so observatories all over the world started following the object, too, in order to calculate its path and figure out its shape.

Interstellar asteroids are thought to be rejects from other planetary systems. When our Solar System first formed, for instance, the giant planets tossed around all the smaller bits of material circulating around the Sun, some of which landed in the outer edges of the Solar System while others were ejected from our neighborhood completely. These outcasts then traveled through interstellar space, possibly passing by other stars. Conceivably, ejected material from other planetary systems must make their way to our Solar System once in a while, says Meech.

Such interstellar objects are thought to pass through our Solar System pretty frequently, but they’re usually moving too fast, and they’re usually too faint to see. With `Oumuamua, astronomers got lucky: the asteroid entered our Solar System at an angle, coming in close by the Sun, and then passed by Earth on its way out of the Solar System. That gave astronomers the chance to catch it with ground-based telescopes. “I think it’s really neat that we had this visitor, however briefly, and we had a chance to look at it up close,” says Meech.

This diagram shows the orbit of the interstellar asteroid ‘Oumuamua as it passes through the Solar System. Unlike all other asteroids and comets observed before, this body is not bound by gravity to the Sun. It has come from interstellar space and will return there after its brief encounter with our star system. Its hyperbolic orbit is highly inclined and it does not appear to have come close to any other Solar System body on its way in.
`Oumuamua’s trajectory through the Solar System.
 Image: European Southern Observatory

After it was first spotted, dozens of observatories all over the world continued to follow it over the next week and a half. Speed was crucial, since `Oumuamua is getting progressively farther away and growing fainter every day. “We had about a window of 10 days or two weeks to do anything practical,” says Meech. Through those quick observations, astronomers found that `Oumuamua had large fluctuations in brightness, indicating an unusually elongated, spinning object that makes one complete rotation every 7.3 hours.

Now, `Oumuamua is 124 million miles from Earth, zooming away at 85,700 miles per hour. It passed by Mars’ orbit on November 1st, and will reach Jupiter’s orbit sometime in 2018. Soon, it’ll be too hard to track, even with Hubble. “It’s really getting much too faint to do anything at all,” says Meech.

But in the next few years, we may be able to spot more interstellar objects like `Oumuamua. Once bigger telescopes start to come online, like the Large Synoptic Survey Telescope that’s being built in Chile, astronomers will be able to see even more visiting rocks. “I predict there will be a lot of these detected in the future,” says Meech.

This Exoplanet’s Hellish Atmosphere Is a Big Deal in the Search For Alien Life



Why This Exoplanet’s Hellish Atmosphere Is a Big Deal in the Search For Alien Life

How observers on Earth can detect molecules on entirely other planets. (Image: ESO education and Public Outreach)

By all accounts, the exoplanet known as WASP-19b is a pretty inhospitable place. As one of the closest known hot-Jupiters to its star—orbiting just two percent of the distance between the Earth and the Sun—it’s home to a scorchingly hot, violent atmosphere. The side of the planet which always faces the star churns with massive convection currents, dredging up heavier molecules from the planet’s lower layers.

Unsuitable for life as it may be, WASP-19b’s proximity to its star happened to make it a perfect candidate for atmospheric observation. A paper published Wednesday in the journal Nature has found the very first evidence of titanium oxide on any known exoplanet, in the upper atmosphere of WASP-19b. And that’s significant for a number of reasons.

“We will be able to constrain models and understand the structure of these atmospheres [and] where they were formed,” Elyar Sedaghati, European Southern Observatory astronomer and co-author of the study, told Gizmodo. “Because if we know what’s in the atmosphere, we can turn the clock back a little bit.”

WASP-19 is a pretty average star about 815 light years away from us, located in the Vela constellation. Its only known planet, WASP-19b, was detected by the Wide Angle Search for Planets in 2009, and it only takes three quarters of a day to orbit its star. That proximity made it a perfect target for a spunky little spectrograph called FORS2 (FOcal Reducer and low dispersion Spectrograph), which was originally installed to the Very Large Telescope in Chile in 1999, almost 20 years ago. But there was work to do before observations could begin.

“[The instrument] had to be upgraded,” said Sedaghati. “All that meant was basically replacing these two prisms that correct for some atmospheric distortions as the star goes near the horizon. These were causing some issues in the exoplanet observations that we were doing with this. So, in November 2014 we made the exchange.” He also hopes with these initial promising results, they go back and do even more improvements on the venerable device.

If you wanted to check on WASP-19b yourself, start here in the Vela constellation (Image: ESO education and Public Outreach)

The researchers began peering at WASP-19b around that time, and they got some intriguing data in something called a light curve, which is the measure of how much the light dims when a planet transits a star. Spectrographs work by observing the light emitted by an object and breaking it into its spectra, much like when you shine white light through a prism and it turns into a rainbow. Using this data, you can determine what kind of chemicals are present in whatever the light is shining through. Because this particular planet is so close to its star, the researchers could see the spectra of its ferociously roiling atmosphere, which extends way further into space than, say, the atmosphere of a more distant gas giant like Jupiter does.

Getting better at decoding the atmospheres of exoplanets, even inhospitable ones like WASP-19b, will contribute to the holy grail of exoplanet research: hunting for signs of life. “Methane — that could be in combination with other molecules, a sign of life — will have very similar absorption features with titanium oxide. This basically gives us hope for future observations for example with the James Webb Telescope,” said Sedaghati.

There are still a lot of steps before that moment, as the JWST won’t launch until the latter half of 2018, and then will need to time scan the skies. But these WASP-19b results are nonetheless encouraging.

“It’s a very nice result,” said Sara Seager, a professor of planetary sciences and physics at MIT, in an email. “I can say this is an outstanding achievement from a ground-based telescope and nature delivered us a fantastic hot planet atmosphere. So far, too many planets are literally “clouded out” and we can’t observe any spectral features. [Titanium Oxide] seems obscure, but is actually a very strong absorber—kind of like a skunk smell, only a tiny amount can make a difference.”

Seager says planets like WASP-19b have a “treasure trove” of features which are really useful to observe.

“It’s an amazing relief to see that planet atmospheres are behaving as expected. Hot planet atmospheres can be nearly as hot as cool star atmospheres and the cool stars are dominated by TiO,” she said.

Jonathan Fortney, an expert in exoplanet atmospheres at UC Santa Cruz, actually predicted that metal oxides would be present in nearby hot-Jupiters. But he admits discoveries in the field will be slow for now because most “general use” instruments can’t pick up the level of detail required for terrestrial exoplanetary atmospheric analysis. Even though the FORS2 tool has been really successful in this project, it was installed before we had even discovered exoplanets using the transit method.

“To me this shows that understanding exoplanet atmospheres is an extremely challenging observational field,” he said. “We must be thoughtful in how we design instruments to detect and understand exoplanet atmospheres. And we must be patient. I really think that this long time lag will be repeated, likely on an even longer time scale, for the atmospheres of temperate terrestrial planets.”

As the study of exoplanet atmospheres continues, be prepared to see stories of successful characterization where the evidence is a little sketchy, Fortney warns.

“People will make claims about these atmospheres, some will end up being correct, some will end up not being correct, and it will take a lot of time for the field to settle out, to correct itself. It will be exciting, but not clear-cut in the first findings,” said Fortney.

Bryson is a freelance storyteller who wants to explore the universe with you.

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