Space Dust, Not an Alien Megastructure, Is to Blame for Star's Bizarre Behavior

NASA/JPL-Caltech
NASA/JPL-Caltech

Space is filled with unsolved mysteries, but rarely do they rivet astronomers and sci-fi fans the way KIC 8462852 has. In 2015, researchers announced that the distant star's light had periodically waned over the course of several years (once by as much as 22 percent), prompting some to theorize that a type of power-harnessing "alien megastructure" could be the culprit. This explanation was largely dismissed, but scientists still didn't know what caused the star's bizarre behavior. Now, Space.com reports that space dust is likely responsible for the mysterious phenomenon.

Published in the journal The Astrophysical Journal Letters [PDF], a new study of KIC 8462852's behavior "shows that different colors of light are being blocked at different intensities," said Tabetha Boyajian, an astronomer at Louisiana State University and the study's lead author, in a statement. "Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure."

KIC 8462852 sits 1500 light-years away from Earth, and is about 50 percent larger and 1000 degrees hotter than the Sun, according to scientists. It's nicknamed "Tabby's star" after Boyajian, who first observed its unusual flickering pattern in 2011 while perusing data from NASA's Kepler Space Telescope with a team of citizen scientists from the online Planet Hunters group. Boyajian and several of the group's members published a paper in 2015 that detailed KIC 8462852's waning and waxing brightness over the course of four years. The data puzzled scientists around the world.

KIC 8462852's otherwise consistent flux was interrupted by sporadic—and substantial—dips in light. Planets can cross in front of distant stars and occlude their light, but even transiting Jupiter-sized planets typically cause a dip of less than 1 percent. In KIC 8462852's case, the difference was up to 22 percent. Further adding to scientists' confusion, KIC 8462852 is an older star that isn't surrounded by the dust and debris from its formation, which can obscure a star's shine.

Theories for the star's behavior ranged from telescope malfunctions to comet fragments moving in an elliptical orbit around the star. Another hypothesis was that a dusty debris disk could be enveloping a black hole located between KIC 8462852 and Earth, National Geographic reports.

Meanwhile, Penn State astronomer Jason Wright hypothesized that alien megastructures, otherwise known as Dyson Spheres, could be harvesting energy from KIC 8462852. (This idea was swiftly debunked.)

To find some answers, Boyajian and colleagues performed follow-up research from March 2016 to December 2017 that was funded through a Kickstarter campaign that raised more than $100,000. Using ground telescopes provided by Las Cumbres Observatory in Goleta, California (and numerous volunteer telescopes around the world), they noted four additional instances in which KIC 8462852 dimmed for stretches of time ranging from days to weeks, according to Gizmodo. (Kickstarter supporters even got to name these instances.)

So far, real-time data from this new study suggests that space dust (perhaps the fragments of a recently destroyed planet or moon) is the likely answer for KIC 8462852's unusual flickering. But no conclusive results have been reached quite yet. For now, the star will continue to stymie scientists. At least they can finally eliminate the phrase "alien megastructure" from their vocabularies.

[h/t Space.com]

How to See the Full Sturgeon Moon on Thursday

Brook Mitchell, Stringer/Getty Images
Brook Mitchell, Stringer/Getty Images

The full moon of every month has a special nickname. Some—like September's harvest moon, December's cold moon, and May's flower moon—have obvious connections to their seasons, while other names are harder to decode. August's sturgeon moon is an example of the latter. It may not be the prettiest lunar title in The Old Farmer's Almanac, but that doesn't mean the event itself on August 15, 2019 won't be a spectacular sight to behold.

What is a Full Sturgeon Moon?

The first (and normally the only) full moon that occurs in August is called a sturgeon moon. The name may have originated with Native American tribes living around the Great Lakes in the Midwest and Lake Champlain in New England. These bodies of water contain lake sturgeon, a species of freshwater fish that grows up to 6.5 feet in length and can live 55 years or longer. August's full moon was dubbed the sturgeon moon to reflect its harvesting season. This full moon is sometimes called the green corn moon, the grain moon, and the blackberry moon for similar reasons.

When to See the Full Sturgeon Moon

On Thursday, August 15, the full sturgeon moon will be highly visible around sunrise and sunset. The satellite will be 99.9 percent illuminated by the sun when it sets Thursday morning at 5:57 a.m EDT—just nine minutes before dawn. On the West Coast, the setting moon will coincide perfectly with the rising sun at 6:15 a.m. PDT.

If you aren't interested in getting out of bed early to catch the sturgeon moon, wait until Thursday evening to look to the horizon. Twenty-seven minutes after sunset, the full moon will rise on the East Coast at 8:21 p.m. EDT. On the West Coast it rises at 8:10 p.m. PDT, 30 minutes after the sun sets.

The moon generally looks bigger and brighter when it's near the horizon, so twilight and dawn are ideal times to catch the spectacle. But it's worth taking another peek at the sky closer to midnight Thursday night; the Perseid meteor shower is currently active, and though the light of the moon may wash them out, you're most likely to spot a shooting star in the late night and early morning hours.

A Full Harvest Moon Is Coming in September

suerob/iStock via Getty Images
suerob/iStock via Getty Images

The Old Farmer's Almanac lists a special name for every month's full moon, from January's wolf moon to December's cold moon. Even if you're just a casual astronomy fan, you've likely heard the name of September's full moon. The harvest moon is the full moon that falls closest to the fall equinox, and it's associated with festivals celebrating the arrival of autumn. Here's what you need to know before catching the event this year.

What is a harvest moon?

You may have heard that the harvest moon is special because it appears larger and darker in the night sky. This may be true depending on what time of night you look at it, but these features are not unique to the harvest moon.

Throughout the year, the moon rises on average 50 minutes later each night than it did the night before. This window shrinks in the days surrounding the fall equinox. In mid-latitudes, the moon will rise over the horizon only 25 minutes to 30 minutes later night after night. This means the moonrise will occur around sunset several evenings in a row.

So what does this mean for the harvest moon? If you're already watching the sunset and you catch the moonrise at the same time, it will appear bigger than usual thanks to something called the moon illusion. It may also take on an orange-y hue because you're gazing at it through the thick filter of the Earth's atmosphere, which absorbs blue light and projects red light. So if you've only seen the full harvest moon around sunset, you may think it always looks especially big and orange, while in reality, any full moon will look that way when it's just above the horizon.

When to See the Harvest Moon

This year, the harvest moon will be visible the night of Saturday, September 14—about a week before the fall equinox on September 23. The moon will reach its fullest state at 12:33 a.m. ET—but if you're still convinced it's not a true harvest moon without that pumpkin-orange color, you can look for it at moonrise at 7:33 p.m. on September 13.

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