More Details Emerge About 'Oumuamua, Earth's First-Recorded Interstellar Visitor

 NASA/JPL-Caltech
NASA/JPL-Caltech

In October, scientists using the University of Hawaii's Pan-STARRS 1 telescope sighted something extraordinary: Earth's first confirmed interstellar visitor. Originally called A/2017 U1, the once-mysterious object has a new name—'Oumuamua, according to Scientific American—and researchers continue to learn more about its physical properties. Now, a team from the University of Hawaii's Institute of Astronomy has published a detailed report of what they know so far in Nature.

Fittingly, "'Oumuamua" is Hawaiian for "a messenger from afar arriving first." 'Oumuamua's astronomical designation is 1I/2017 U1. The "I" in 1I/2017 stands for "interstellar." Until now, objects similar to 'Oumuamua were always given "C" and "A" names, which stand for either comet or asteroid. New observations have researchers concluding that 'Oumuamua is unusual for more than its far-flung origins.

It's a cigar-shaped object 10 times longer than it is wide, stretching to a half-mile long. It's also reddish in color, and is similar in some ways to some asteroids in our solar system, the BBC reports. But it's much faster, zipping through our system, and has a totally different orbit from any of those objects.

After initial indecision about whether the object was a comet or an asteroid, the researchers now believe it's an asteroid. Long ago, it might have hurtled from an unknown star system into our own.

'Oumuamua may provide astronomers with new insights into how stars and planets form. The 750,000 asteroids we know of are leftovers from the formation of our solar system, trapped by the Sun's gravity. But what if, billions of years ago, other objects escaped? 'Oumuamua shows us that it's possible; perhaps there are bits and pieces from the early years of our solar system currently visiting other stars.

The researchers say it's surprising that 'Oumuamua is an asteroid instead of a comet, given that in the Oort Cloud—an icy bubble of debris thought to surround our solar system—comets are predicted to outnumber asteroids 200 to 1 and perhaps even as high as 10,000 to 1. If our own solar system is any indication, it's more likely that a comet would take off before an asteroid would.

So where did 'Oumuamua come from? That's still unknown. It's possible it could've been bumped into our realm by a close encounter with a planet—either a smaller, nearby one, or a larger, farther one. If that's the case, the planet remains to be discovered. They believe it's more likely that 'Oumuamua was ejected from a young stellar system, location unknown. And yet, they write, "the possibility that 'Oumuamua has been orbiting the galaxy for billions of years cannot be ruled out."

As for where it's headed, The Atlantic's Marina Koren notes, "It will pass the orbit of Jupiter next May, then Neptune in 2022, and Pluto in 2024. By 2025, it will coast beyond the outer edge of the Kuiper Belt, a field of icy and rocky objects."

Last month, University of Wisconsin–Madison astronomer Ralf Kotulla and scientists from UCLA and the National Optical Astronomy Observatory (NOAO) used the WIYN Telescope on Kitt Peak, Arizona, to take some of the first pictures of 'Oumuamua. You can check them out below.

Images of an interloper from beyond the solar system — an asteroid or a comet — were captured on Oct. 27 by the 3.5-meter WIYN Telescope on Kitt Peak, Ariz.
Images of 'Oumuamua—an asteroid or a comet—were captured on October 27.
WIYN OBSERVATORY/RALF KOTULLA

U1 spotted whizzing through the Solar System in images taken with the WIYN telescope. The faint streaks are background stars. The green circles highlight the position of U1 in each image. In these images U1 is about 10 million times fainter than the faint
The green circles highlight the position of U1 in each image against faint streaks of background stars. In these images, U1 is about 10 million times fainter than the faintest visible stars.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Color image of U1, compiled from observations taken through filters centered at 4750A, 6250A, and 7500A.
Color image of U1.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Editor's note: This story has been updated.

A Rare Unicorn Meteor Outburst Could Be Visible for Less Than an Hour on Thursday

joegolby/iStock via Getty Images
joegolby/iStock via Getty Images

Your chances of seeing a unicorn this week are slim, but if you look up on Thursday night, you may see something that's almost as extraordinary. As Sky & Telescope reports, the upcoming Alpha Monocerotid meteor shower could produce a meteor outburst, which means there could be multiple shooting stars per second streaming from the unicorn constellation.

What is a unicorn meteor shower?

There's nothing particularly magical about the Alpha Monocerotids. They appear to originate near the star Procyon, which is next to the constellation Monoceros, the Greek name for unicorn.

The shower is known for occasionally packing a dense flurry of activity into a brief viewing window. The meteors appear between November 15 through the 25th of each year, and peak around the 22nd. Several times a century, the shower treats sky gazers to an "outburst" of shooting stars that lasts less than an hour.

Such an outburst is predicted for 2019. According to astronomers Peter Jenniskens and Esko Lyytinen, the Earth is on track to pass through a thick portion of the tail of the unknown comet that provides debris for the shower. The conditions are almost the same as they were in 1995, when the Alpha Monocerotids lit up the sky at a rate of 400 meteors per hour, which is approaching meteor storm levels. For that reason, the scientists are expecting shooting stars to appear in the same numbers this time around.

How to see the meteor outburst

Timing is crucial if you want to catch the Alpha Monocerotids, even more than with regular meteor showers. The outburst is expected to start at 11:15 p.m. EST and last just 15 to 40 minutes. Luckily, the sun will be fully set by then and the crescent moon won't rise until after 2 a.m, creating optimal viewing conditions for the eastern half of the country. The shooting stars are fast—traveling at 40 miles per second—and they come at random. Don't be surprised to wait a minute between meteors during some parts of the outburst and less than a second at others.

[h/t Sky & Telescope]

The Leonid Meteor Shower Peaks This Weekend—Here's the Best Way to Watch It

mdesigner125/iStock via Getty Images
mdesigner125/iStock via Getty Images

We're nearing the end of 2019, but there are still a few astronomical events to catch before the year is s out. This Sunday—November 17—the Leonid meteor shower is expected to peak. Here's everything you need to know before viewing the spectacle.

What is the Leonid meteor shower?

Like all meteor showers, the Leonids are caused by meteoroids from outer space burning up on their descent toward Earth. These particular shooting stars come from the rocky tail of Comet 55P/Tempel-Tuttle. Each November, debris from the comet pummels the Earth's atmosphere, causing meteors to light up the sky at rates that can exceed 1000 per hour.

The Leonids won't reach that frequency this year. According to EarthSky, the meteors would peak at a rate of around 10 to 15 per hour in a dark, moonless sky. But because the moon will be bright this weekend, sky-gazers will likely see less of them, with only the brightest shooting stars shining through.

How to See the Leonids

For your best chance of spotting the Leonids, look up the night of Sunday, November 17 and early in the morning of Monday, November 18. The shower reaches its peak after midnight. The moon will be in its waning gibbous phase at that time, so even with clear skies, viewing conditions won't be ideal. But there are ways to increase your chances of seeing as many meteors as possible. Try finding a large object to stand under—such as a tree or building—that will block your view of the moon. If you don't see anything right away, be patient: The more time you give your eyes to adjust to the darkness, the more likely you are to spot a shooting star.

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