On Monday, August 21, North America will be treated to dazzling views of a total solar eclipse. But what if humans lived someplace else in the solar system—would eclipses be regarded with the same excitement and awe as they are here on Earth?
In her new video, Physics Girl Dianna Cowern investigates what these celestial events look like beyond our home planet. She discovers that, on some planets, total solar eclipses aren't even possible. The two moons orbiting Mars, for example, are too small to completely block the Sun. Move on to other parts of the solar system and you'll find places where total eclipses aren't rare at all. On Jupiter, which has 69 moons, it's possible for there to be multiple eclipses occurring at the same time. On Pluto, whose moon appears much larger in its sky than the Sun, total eclipses can happen every day for years on end.
Considering all the factors required to make a perfect solar eclipse, we're pretty lucky to be able to see one from Earth at all. And if you're close enough to the path of totality to view this year's North American eclipse, you can consider yourself even luckier.
The Leonid meteor shower will be making its annual appearance in the sky this weekend. As NPR reports, the best time to catch it will be late Saturday night into Sunday morning (November 17-18)—so if you really want to catch this dazzling light show, you may want to drink some coffee to help you stay up.
The waxing gibbous Moon will dull the meteors’ shine a little, so plan to start stargazing after the Moon has set but before dawn on Sunday. (You can use timeanddate.com to figure out the moonset time in your area. The site also features an interactive meteor shower sky map to track visibility conditions.)
If you'll be in parts of the South or Midwest this weekend, you're in luck. Florida, Alabama, Mississippi, Nebraska, and Nevada are expected to enjoy the best view of the Leonids this time around, according to Popular Mechanics.
The Leonids occur every year around November 17 or 18, when Earth drifts across the long trail of debris left behind by the comet Tempel-Tuttle. The comet takes 33 years to complete its orbit around the Sun, and when it reaches perihelion (its closest approach to the Sun), a Leonid storm may occur depending on the density of the comet's existing debris. This sometimes results in hundreds of thousand of meteors streaking across the sky per hour, viewable from Earth. The last Leonid storm occurred in 2001, but Earth may not see dense debris clouds until 2099, according to the American Meteor Society.
This year, if skies are clear and you can secure a secluded spot away from city lights, you might be able to see around 15 to 20 meteors per hour. They travel at 44 miles per second “and are considered to be some of the fastest meteors out there,” NASA says. They’re also known for their “fireballs”—explosions of light and color—which tend to last longer than a typical meteor streak.
An odd, cigar-shaped object has been stumping scientists ever since it zoomed into our solar system last year. Dubbed 'Oumuamua (pronounced oh-MOO-ah-MOO-ah), it was first seen through the Pan-STARRS 1 telescope in Hawaii in October 2017. 'Oumuamua moved at an unusually high speed and in a different kind of orbit than those of comets or asteroids, leading scientists to conclude that it didn't originate in our solar system. It was the first interstellar object to arrive from somewhere else, but its visit was brief. After being spotted over Chile and other locales, 'Oumuamua left last January, leaving lots of questions in its wake.
Now, two researchers at Harvard University bury a surprising suggestion in a new paper that analyzes the object's movement: 'Oumuamua could be an alien probe. Sure, why not?
First, astrophysicists Shmuel Bialy and Abraham Loeb argue that 'Oumuamua is being driven through space by solar radiation pressure, which could explain its uncharacteristic speed. But for that theory to work, they calculate that the object must be unusually thin. Bialy and Loeb then analyze how such a slender object might withstand collisions with dust and gases, and the force of rotation, on its interstellar journey.
Then things get weird.
"A more exotic scenario is that 'Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization," they write [PDF]. They suggest that ‘Oumuamua could be be a lightsail—an artificial object propelled by radiation pressure—which also happens to be the technology that the Breakthrough Starshot initiative, of which Loeb is the advisory committee chair, is trying to send into space. "Considering an artificial origin, one possibility is that 'Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment,” they write.
Their paper, which was not peer-reviewed, was posted on the pre-print platform arXiv.
Loeb is well known for theorizing about alien tech. He previously suggested that intense radio signals from 2007 could be the work of aliens who travel through space on solar sails. However, Loeb acknowledged that this theory deals more with possibility than probability, The Washington Post noted. “It’s worth putting ideas out there and letting the data be the judge,” Loeb told the paper last year.