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Small Asteroid Gives Earth a Close Shave in Highly Anticipated Flyby

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A small asteroid buzzed Earth early Thursday (Oct. 12) in a close flyby that scientists had been looking forward to for months.

The space rock, known as 2012 TC4, zoomed about 26,000 miles (42,000 kilometers) above Antarctica at 1:42 a.m. EDT (0542 GMT) Thursday. That’s about 11 percent the distance between Earth and the moon, and just beyond the orbit of geostationary satellites.

There was never any danger of an impact during this flyby, NASA researchers stressed. And 2012 TC4 is almost certainly too small to cause any serious concern, even if it did line up Earth in its crosshairs. (Before the flyby, scientists estimated the asteroid’s diameter to be between 33 feet and 50 feet, or 10 to 15 meters.) [Famous  Asteroid Flybys and Close Calls (Infographic)]

“The impact effects would be simply a flash through the atmosphere and a breakup — a very bright fireball, basically,” Paul Chodas, manager of the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory in Pasadena, California, told Space.com. 

Artist’s illustration showing the small asteroid 2012 TC4 zooming by Earth on Oct. 12, 2017.

Credit: NASA/JPL-Caltech

But Chodas and other asteroid researchers around the world were keenly interested in the flyby nonetheless. They’ve been tracking 2012 TC4 for months, as a sort of dry run for dealing with an approaching asteroid that may indeed pose a threat to Earth.

“This campaign is a team effort that involves more than a dozen observatories, universities and labs around the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities,” campaign leader Vishnu Reddy, an assistant professor at the University of Arizona’s Lunar and Planetary Laboratory, said in a statement.

“This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination and international communications,” Reddy added.

Diagram showing the asteroid 2012 TC4's flyby of Earth on Oct. 12, 2017.

Diagram showing the asteroid 2012 TC4’s flyby of Earth on Oct. 12, 2017.

Credit: NASA/JPL-Caltech

Among the telescopes that were involved is the big radar dish at NASA’s Goldstone Deep Space Communications Complex in the California desert, whose observations should help scientists nail down 2012 TC4’s size, Chodas said. (The Arecibo Observatory in Puerto Rico also would have been participating, he added, but it’s been offline since Hurricane Maria pounded the island.)

But don’t expect great radar images of the asteroid, as Goldstone and Arecibo have generated for other, much larger asteroids; 2012 TC4 is likely too small for any significant surface features to be resolved by radar, Chodas said.

Other scopes were slated to gather composition data during the flyby — information that should shed light on the space rock’s density, Chodas said. And scientists should have a good idea of 2012 TC4’s precise orbit in the aftermath of the encounter as well, he added.

As its name suggests, 2012 TC4 was discovered in 2012, by the Panoramic Survey Telescope & Rapid Response System in Hawaii. The asteroid flew past Earth that year — oddly enough, also on Oct. 12.

But the space rock dropped off the map shortly after that 2012 flyby, speeding beyond telescopes’ reach into the dark depths of the solar system. And now astronomers have welcomed it back with open arms.

Thursday’s flyby “was rather special in the sense that we don’t often know about small asteroids approaching the Earth years in advance,” Chodas said.

“It’s interesting to study such a small object, but it’s also very appropriate, because we’re more likely to see a small asteroid heading for Earth impact than a large one, simply because there are far more small ones than large ones,” he added.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

Space.com is the premier source of space exploration, innovation and astronomy news, chronicling (and celebrating) humanity's ongoing expansion across the final frontier. We transport our visitors across the solar system and beyond through accessible, comprehensive coverage of the latest news and discoveries. For us, exploring space is as much about the journey as it is the destination. So from skywatching guides and stunning photos of the night sky to rocket launches and breaking news of robotic probes visiting other planets, at Space.com you’ll find something amazing every day.

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Bizarre Blue 'Flashes and Glows' May Reveal Thunderstorm Secrets

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Bright, blue flashes stretch from the tops of powerful thunderstorms toward the edge of space, providing a fascinating celestial show for astronauts on the International Space Station, and now, scientists are learning more about these showstopping displays. 

In 2015, European Space Agency astronaut Andreas Mogensen captured a video of the strange blue flashes dancing above the clouds as the space station passed over the Bay of Bengal. 

These features are called blue jets — a type of transient luminous event (TLE) resulting from activity in and below powerful thunderstorms on Earth. One of the photographs captured by Mogensen showed a pulsating blue jet that stretched 25 miles (40 kilometers) above sea level, according to a statement from NASA. [Earth From Space: Amazing Astronaut Photos]

Using these observations, researchers from Denmark’s National Space Institute studied the elusive features to learn more about how storms form and develop over time. Their findings showed that 245 pulsating blue discharges were observed during the 160 seconds of video footage, which is equal to roughly 90 blue-jet flashes per minute, the researchers said in a new study describing the findings. 

The study also revealed evidence of red sprites, which glow in the upper atmosphere following large lightning flashes on Earth. Red sprites are difficult to detect because they last only a few milliseconds. 

In fact, visual evidence of TLEs wasn’t available until 1989. Some of the first observations of these events were of red sprites photographed by cameras on board the space shuttle, as well as from images taken during a NASA and University of Alaska airborne campaign. 

Recently, however, astronauts aboard the space station have been able to capture various natural light shows on camera, including red sprites over two different storms within 3 minutes of each other — first over the American Midwest and then later near the coast of El Salvador. These red sprites, which were spotted in August 2015, stretched roughly 60 miles (100 km) above Earth, according to the statement

Observations of strange atmospheric features like red sprites and blue jets help improve researchers’ understanding of lightning and thunderstorms, which can lead to better storm models and weather forecasts. Furthermore, researchers also aim to learn more about why storms produce different TLEs in different circumstances. 

“TLE studies have been, to an extent, fortunate observation,” Tim Lang, an atmospheric scientist at NASA’s Marshall Space Flight Center, said in the statement. “We’ve gotten better at finding them, but it’s mostly case-based analysis.”

Researchers will soon have the opportunity to capture even better storm observations from space using NASA’s Lightning Imaging Sensor, which was installed on the orbiting lab in February 2017, and the Atmosphere-Space Interactions Monitor, which is slated to launch to the space station later this year. These instruments will allow researchers to analyze storms from both below and above, and closely examine thunderstorms’ impact on Earth’s atmosphere. 

Follow Samantha Mathewson @Sam_Ashley13. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

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NASA Moon Probe Celebrates 100th Lunar Day

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October means baseball playoffs, Halloween and, for NASA’s Lunar Reconnaissance Orbiter, 100 lunar days on the moon. 

A lunar day is a lot longer than a day on Earth, according to a new NASA video. We measure days from noon to noon or sunset to sunset. On Earth, a day takes 24 hours, though it will vary by a up to 29 seconds because of the eccentricity of Earth’s orbit. On the moon, a day is 708.7 hours, or 29.53 Earth days. On Oct. 16, the probe hit the 100 lunar-day mark.

That day length is about the same amount of time it takes for the moon to make a complete revolution around the Earth, and that’s no accident. The moon is tidally locked to the Earth, and always presents the same face to us. So its rotation period and orbital period are the same.

The Earth’s orbital and rotation periods are of course very different, with our planet making one rotation in 24 hours, but completing one orbit in a year. Since the Earth moves around the sun in a roughly circular orbit, when one rotation is finished the sun will appear slightly west of its position in the sky at the same time the day before. The Earth also wobbles a bit, which alters the length of a day by a small amount. 

A similar thing happens to the moon. The 100 days LRO passed are mean solar days — an average. The length of a day on the moon can vary, being 6 hours shorter or up to 7 hours longer than the mean of 28.53 Earth days, for the same reasons that the Earth’s day can vary, plus one other: The moon’s orbit is not a perfect circle. The moon also wobbles a bit from side to side (a phenomenon called libration), so from Earth a sliver of the far side is periodically visible. 

Launched on June 18, 2009, LRO was originally planned to last about a year. It has been extended numerous times since then. The probe orbits between 12 miles (20 kilometers) and 103 miles (165 km) above the lunar surface, investigating the lunar topography and radiation environment, keeping an eye out for water. 

You can follow SPACE.com on Twitter @Spacedotcom. We’re also on Facebook & Google+. Original article on Space.com.

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Supermoon 2017: When and How to See December’s 'Full Cold Moon'

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A “supermoon” rises over the U.S. Capitol Building in this NASA photo captured on July 31, 2015. Another supermoon will rise on Sunday (Dec. 3, 2017).

When the “Full Cold Moon” rises on Dec. 3, it will also be the first and last “supermoon” of 2017. 

Supermoons happen when a full moon approximately coincides with the moon’s perigee, or a point in its orbit at which it is closest to Earth. This makes the moon appear up to 14 percent larger and 30 percent brighter than usual. 

The moon becomes totally full at 10:46 a.m. EST (1546 GMT) on Sunday (Dec. 3). It will officially reach perigee the next day (Dec. 4) at 3:45 a.m. EST (0845 GMT), when it is 222,135 miles (357,492 kilometers) away from Earth. [Supermoon Secrets: 7 Surprising Big Moon Facts]

While the moon’s average distance is 238,000 miles (382,900 km) from Earth, its orbit isn’t perfectly circular, so that distance varies a small amount. When it reaches apogee, or its farthest distance from Earth, on Dec. 19, it will be 252,651 miles (406,603 km) away. That’s a difference of 30,516 miles (48,110 km) — but the moon’s distance from Earth can vary more than that. 

The perigee for December’s supermoon won’t even be the closest this year; that happened May 25, when the not-so-super new moon was 221,958 miles (357,208 km) away from Earth. That date didn’t coincide with a full moon, though, so it didn’t qualify as a supermoon. 

Credit: Karl Tate/SPACE.com

Supermoons don’t happen every month because the moon’s orbit changes orientation as the Earth goes around the sun. So, the long axis of the moon’s elliptical path around the Earth points in different directions, meaning that a full (or new) moon won’t always happen at apogee or perigee. 

In New York City, the full moon will rise the evening of Dec 3. at 4:59 p.m. local time. Moonset will be the morning of Dec. 4 at 7:50 a.m., according to timeanddate.com. The sun sets at 4:28 p.m. on Dec. 3, so the full moon and the sun will not be visible at the same time, at least in New York. 

If you want to see both in the sky at once, you need to go below the equator. In Wellington, New Zealand, the full moon happens at 4:46 a.m. local time on the morning of Dec. 4, and sets at 6:10 a.m., half an hour after the sun rises at 5:41 a.m. 

Look for the full moon in the constellation of Taurus. Though the moon is officially full on Dec. 3, it will still appear full to the casual observer the night before and after. 

As it did in November, the full moon will pass in front of, or “occult,” the bright star Aldebaran. This event will be visible from northern Canada, Alaska, eastern Russia, Kazakhstan, much of China and as far south as Bangladesh. 

In the continental U.S., residents of Washington state can catch the occultation; People in Seattle will see the predawn moon pass in front of Aldebaran at 6:09 a.m. local time, reappearing at 6:46 a.m. In Boise, Idaho, the occultation will start at 7:15 a.m., but skywatchers there won’t get to see Aldebaran reappear from behind the moon, as the occultation ends after the moon sets at 7:43 a.m. 

In Anchorage, Alaska, Aldebaran disappears behind the moon at 4:38 a.m. local time and reappears at 5:32 a.m. The moon becomes full soon after that at 6:46 a.m. local time, setting at 9:20 a.m. Canadian observers in Vancouver will see the occultation start at 6:06 a.m. and end at 6:46 a.m. (Full moon is at 7:46 a.m.)

Observers in Asia will see more of the occultation. In Beijing, the event starts at 7:54 p.m. local time and ends at 8:37 p.m. — better timed for those who’d rather not get up too early. 

According to the Old Farmer’s Almanac, the name of the full moon in December is “Full Cold Moon,” and given the weather in December (at least in the Northern Hemisphere), that’s not a surprise. 

This is also reflected in the names from native peoples of North America. According to the Ontario Native Literacy Project, the Ojibwe called December’s full moon “Mnidoons Giizis,” the “Big Spirit Moon” or “Blue Moon.” For the Ojibwe, it marked the 12th calendar month, and was a time for healing. The Haida of the Pacific Northwest called it the “Snow Moon,” or “Ta’aaw Kungaay.” 

Among the Hopi, whose ceremonial life revolved around the lunar and solar cycles, the lunation just before the winter solstice was the “Sparrow-Hawk” moon, as noted by Janet Sharp of Washburn University in her study of Hopi mathematical concepts and teaching.  

In the Southern Hemisphere, December is summertime. The Māori of New Zealand described the lunar months in November to December as Hakihea, or “birds are now sitting in their nests,” according to the Encyclopedia of New Zealand. 

In China, the traditional lunar calendar calls the December lunation the 10th month. Called Yángyuè, or Yang month, it’s named for the yang ― the masculine, positive principle of Taoism familiar to Westerners as part of the yin and yang.  

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