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Wikimedia Commons
Wikimedia Commons

The Last Time a (Really Big) Meteor Hit Russia

Wikimedia Commons
Wikimedia Commons

In late 1908, the scientific community in St. Petersburg and Moscow was galvanized by vague reports filtering out of Siberia, telling of a gigantic, mysterious explosion that summer that had been witnessed only by a handful of native Evenki tribesmen and Russian settlers.

According to eyewitness reports gathered later by Leonid Kulik, at 7:17 am on June 30, 1908, a column of bright blue light became visible in the sky above central Siberia, followed by a huge explosion near Tunguska, a remote region located in the taiga (pine forest) northwest of Lake Baikal.

The explosion rocked the earth, leveled gigantic swaths of forest, and filled the sky with blinding light, according to one Evenki native, who later remembered: “Then I saw a wonder: trees were falling, the branches were on fire, it became mighty bright, how can I say this, as if there was a second sun, my eyes were hurting, I even closed them.” A Russian settler reported that the explosion blew out windows in buildings up to 40 miles away from the impact, accompanied by intense heat: “At that moment I became so hot that I couldn't bear it, as if my shirt was on fire… hot wind raced between the houses, like from cannons…” The explosion clearly occurred some distance above the ground, with one eyewitness recalling that “the sky split in two and fire appeared high and wide over the forest.”

The effects of the Tunguska Event were breathtaking: the explosion, measuring between 10 and 20 megatons (somewhere between 435 and 870 times the force of the Nagasaki bomb), leveled approximately 80 million trees over an area of 800 square miles, or around half a million acres. No surprise, the simple peasant folk who witnessed it assumed the worst, with one newspaper reporting that “women cried, thinking it was the end of the world.” Later, particulate matter in the atmosphere produced stunning sunsets around the world.

It’s still not clear what caused the Tunguska Event, but based on the eyewitness reports and butterfly-shaped blast pattern, most scientists agree it must have resulted from a meteor or comet exploding about six miles above the ground. The latest theory suggests the object measured around 100 feet across and weighed over 600,000 tons; that’s about three times the size of the world’s largest ocean liners, which weigh in at around 225,000 tons. Interestingly, many eyewitnesses described not just one but a series of explosions, raising the possibility that the event was caused by a string of meteors or parts of a disintegrating comet hitting the earth in succession.

However scientific expeditions led by Kulik beginning in 1921 were unable to recover any fragments of the meteor or comet, and subsequent investigations (including an Italian mission which may have found a crater caused by the explosion in 2007) have also come up empty-handed. Predictably, this has given rise to all sorts of bizarre conspiracy theories, including, yes, an extraterrestrial visitation. Why aliens would want to destroy a remote part of Siberia, and what they have against pine trees, remains unclear.

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Scott Butner, Flickr // CC BY-NC-ND 2.0
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Space
Look Up! The Lyrid Meteor Shower Arrives Saturday Night
Scott Butner, Flickr // CC BY-NC-ND 2.0
Scott Butner, Flickr // CC BY-NC-ND 2.0

There is a thin line between Saturday night and Sunday morning, but this weekend, look up and you might see several of them. Between 11:59 p.m. on April 21 and dawn on Sunday, April 22, the Lyrid meteor shower will peak over the Northern Hemisphere. Make some time for the celestial show and you'll see a shooting star streaking across the night sky every few minutes. Here is everything you need to know.

WHAT IS THE LYRID METEOR SHOWER?

Every 415.5 years, the comet Thatcher circles the Sun in a highly eccentric orbit shaped almost like a cat's eye. At its farthest from the Sun, it's billions of miles from Pluto; at its nearest, it swings between the Earth and Mars. (The last time it was near the Earth was in 1861, and it won't be that close again until 2280.) That's quite a journey, and more pressingly, quite a variation in temperature. The closer it gets to the Sun, the more debris it sheds. That debris is what you're seeing when you see a meteor shower: dust-sized particles slamming into the Earth's atmosphere at tens of thousands of miles per hour. In a competition between the two, the Earth is going to win, and "shooting stars" are the result of energy released as the particles are vaporized.

The comet was spotted on April 4, 1861 by A.E. Thatcher, an amateur skywatcher in New York City, earning him kudos from the noted astronomer Sir John Herschel. Clues to the comet's discovery are in its astronomical designation, C/1861 G1. The "C" means it's a long-period comet with an orbit of more than 200 years; "G" stands for the first half of April, and the "1" indicates it was the first comet discovered in that timeframe.

Sightings of the Lyrid meteor shower—named after Lyra, the constellation it appears to originate from—are much older; the first record dates to 7th-century BCE China.

HOW CAN I SEE IT?

Saturday night marks a first quarter Moon (visually half the Moon), which by midnight will have set below the horizon, so it won't wash out the night sky. That's great news—you can expect to see 20 meteors per hour. You're going to need to get away from local light pollution and find truly dark skies, and to completely avoid smartphones, flashlights, car headlights, or dome lights. The goal is to let your eyes adjust totally to the darkness: Find your viewing area, lay out your blanket, lay down, look up, and wait. In an hour, you'll be able to see the night sky with great—and if you've never done this before, surprising—clarity. Don't touch the smartphone or you'll undo all your hard ocular work.

Where is the nearest dark sky to where you live? You can find out on the Dark Site Finder map. And because the shower peaks on a Saturday night, your local astronomy club is very likely going to have an event to celebrate the Lyrids. Looking for a local club? Sky & Telescope has you covered.

WHAT ELSE IS GOING ON UP THERE?

You don't need a telescope to see a meteor shower, but if you bring one, aim it south to find Jupiter. It's the bright, unblinking spot in the sky. With a telescope, you should be able to make out its stripes. Those five stars surrounding it are the constellation Libra. You'll notice also four tiny points of light nearby. Those are the Galilean moons: Io, Europa, Ganymede, and Callisto. When Galileo discovered those moons in 1610, he was able to prove the Copernican model of heliocentricity: that the Earth goes around the Sun.

THERE'S BAD WEATHER HERE! WHAT DO I DO?

First: Don't panic. The shower peaks on the early morning of the 22nd. But it doesn't end that day. You can try again on the 23rd and 24th, though the numbers of meteors will likely diminish. The Lyrids will be back next year, and the year after, and so on. But if you are eager for another show, on May 6, the Eta Aquariids will be at their strongest. The night sky always delivers.

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Space
New NASA Satellite Called TESS Could Discover Thousands of New Planets

Since NASA’s Kepler spacecraft launched in 2009, the space agency has found and confirmed a whopping 2343 new planets. Of those, 30 are considered to be situated in a “habitable zone,” an area in which a planet’s surface could theoretically contain water.

A new satellite, set to launch today, is expected to find thousands more planets outside of our solar system, known as exoplanets. TESS, short for the Transiting Exoplanet Survey Satellite, is NASA’s latest effort to plumb the depths and darkness of outer space in search of other Earth-like planets—including those that could potentially support life.

TESS is slated to complete a two-year survey of the “solar neighborhood,” a general region which comprises more than 200,000 of the brightest nearby stars. To find these outlier planets, NASA scientists will be keeping an eye out for temporary changes in brightness, which indicate that a planet is blocking its host star.

According to Martin Still, the program scientist working on the TESS mission, the launch comes “with certainty” that TESS will find many nearby exoplanets. "We expect to find a whole range of planet sizes, between planets the size of Mercury or even the Moon—our Moon—to planets the same size as Jupiter and everything in between,” Still said in a NASA interview.

While the Kepler mission was considered a major success, NASA noted that most of the planets it recorded are those that orbit faint, faraway stars, making it difficult to conduct follow-up observations. The stars that TESS plans to survey will be 30 to 100 times brighter than those observed by its predecessor. This allows for newly detected planets and their atmospheres to be characterized more easily.

“Before Kepler launched, we didn't know for sure if Earth-sized planets existed,” Elisa V. Quintana, a NASA astrophysicist, told Reddit. “Kepler was a statistical survey that looked at a small patch of sky for four years and taught us that Earths are everywhere. TESS is building on Kepler in the sense that TESS wants to find more small planets but ones that orbit nearby, bright stars. These types of planets that are close to us are much more easy to study, and we can measure their masses from telescopes here on Earth.”

The most common categories of exoplanets are Earth- and Super Earth–sized masses—the latter of which are larger than Earth but smaller than Uranus and Neptune.

TESS is scheduled to launch from the Cape Canaveral Air Force Station in Florida on a SpaceX Falcon 9 rocket at 6:32pm EDT today.

For more information about TESS, check out this video from NASA.

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