The 2018 Leonid Meteor Shower

Nov. 16, 2018: Earth is entering a stream of debris from comet Tempel-Tuttle, source of the annual Leonid meteor shower. Last night, NASA’s network of all-sky meteor cameras detected five Leonid fireballs over the USA, numbers that will grow as we enter the weekend. Forecasters expect the shower to peak on Nov. 17th and 18th with rates as high as 15 meteors per hour.

The Leonids are famous for storming. As often as a few times each century, Earth hits a dense filament of Comet Tempel-Tuttle’s dusty debris, causing thousands of meteors per hour to stream out of the constellation Leo. Such a display in 1833 kickstarted modern meteor astronomy with an outburst of 100,000 Leonids per hour. Many readers still remember the Leonid fireballs of 1998 and the meteor storms of 1999, 2001 and 2002.

2018 is not a storm year, however. Earth will thread the needle between dense filaments, scooping up a lesser amount of dust. Each speck will hit Earth’s upper atmosphere at ~72 km/s (160,000 mph) producing a swift meteor emerging from the constellation Leo. The best time time to look is during the hours before dawn on Saturday, Nov. 17th, and Sunday, Nov. 18th, when the Lion is high in the southeastern sky.

If you do set your alarm for dawn, there’s more to see besides Leonids. For one thing, amateur astronomers have just discovered a new comet in the constellation Virgo. Comet Machholz-Fujikawa-Iwamoto (C/2018 V1) is an easy target for backyard telescopes, shining like a green fuzzy star of 8th magnitude. Use these orbital elements to point your optics.

Not far from the comet, Venus is having a close encounter with the brightest star in Virgo, Spica. Alan Dyer photographed the pair rising over the plains of Alberta, Canada, yesterday morning:

“Venus and Spica rose together as morning stars in the dawn twilight on Nov. 15th,” says Dyer. “Light clouds added the natural glows and enlarged Venus, so it really does look ‘big’ here!”

The Orionid Meteor Shower

Oct. 19, 2018: Right now, specks of dust from Halley’s Comet are disintegrating in Earth’s atmosphere, kicking off the annual Orionid meteor shower. NASA cameras caught more than a dozen Orionid fireballs streaking across the USA during the past 48 hours, and the show is expected to improve during the weekend as Earth moves deeper into Halley’s stream of debris:

fireball_strip2

Above: This Orionid fireball, observed by Maciek Myszkiewicz in Oct. 2012, was as bright as a full Moon.

“The upcoming Orionids should provide a fairly good show for most visual observers,” says Peter Brown of the University of Western Ontario Meter Physics Group. “The shower’s radiant is already quite active and well defined in data from the Canadian Meteor Orbit Radar (CMOR).”

Orionids appear every year around this time when Earth crosses Halley’s debris stream, with the shower typically producing about 20 meteors per hour. Some of the brightest stars and constellations in the sky–e.g., Orion the Hunter, Sirius the Dog Star, and Taurus the Bull–form the shower’s backdrop. This makes the display extra-beautiful in disproportion to the raw number of meteors.

Some years, however, are even better than others. “Most notable was a short-lived outburst of relatively bright Orionids in 1993 observed several days before the predicted peak. This hints that there may be narrow filaments of larger meteoroids embedded in the overall debris stream,” says Brown. “We also observed enhanced Orionid activity in the years 2006 through 2009 with rates 2 to 3 times normal.”

This year’s shower has one thing going against it: The nearly full Moon. Lunar glare could reduce visible meteor rates 2- or 3-fold. The best time to look, therefore, is during the dark hours before sunrise when the Moon is sinking below the western horizon and the shower’s radiant in Orion is high in the southeast: sky map.

“Finding dark skies and clear weather in the early morning hours of Sunday, Oct 21st, just after the moon sets this year is the surest way to see these messengers from 1P/Halley,” says Brown. Enjoy the show!

Realtime Meteor Photo Gallery

 

Earth Dodges a Meteor Storm

Oct. 13, 2018: On Oct. 8-9, Europeans outdoors around midnight were amazed when a flurry of faint meteors filled the sky. “It was a strong outburst of the annual Draconid meteor shower,” reports Jure Atanackov, a member of the International Meteor Organization who witnessed the display from Slovenia. Between 22:00 UT (Oct. 8) and 01:00 UT (Oct. 9), dark-sky meteor rates exceeded 100 per hour. In eastern France, Tioga Gulon saw “1 to 2 meteors per minute,” many of them shown here in an image stacked with frames from his video camera:

“It was a rare and impressive event,” says Atanackov.

It could easily have been 10 times more impressive. In fact, Earth narrowly dodged a meteor storm.

The European outburst occurred as Earth skirted a filament of debris from Comet 21P/Giacobini-Zinner. If that filament had shifted in our direction by a mere 0.005 AU (~500,000 miles), Earth would have experienced a worldwide storm of 1000+ meteors per hour. These conclusions are based on a computer model of the comet’s debris field from the University of Western Ontario’s Meteor Physics Group. Here it is, showing Earth shooting the gap between two filaments of comet dust:

Western Ontario postdoctoral researcher Auriane Egal created the model and predicted the outburst before it happened. Egal’s model was in good agreement with a rival model from NASA, so confidence was high. Meteors seen over Europe came from the larger filament on the right.

According to the models, Earth’s L1 and L2 Lagrange points were both forecast to have storm-level activity–especially L2 which would experience the Earth-equivalent of 4000+ meteors per hour. This prompted NASA to take a close look at the danger to spacecraft.

“The US has four space weather spacecraft at L1: ACE, SOHO, Wind, and DSCOVR,” says Bill Cooke of NASA’s Meteoroid Environment Office. “There is only one operational spacecraft at L2 – the European Space Agency’s GAIA – which was where most of the Draconid activity was expected to take place. GAIA shut down science operations for a few hours around the projected storm peak and re-oriented to turn the hard side of the vehicle towards the incoming debris. All of the spacecraft came through the Draconids without incident, and this shower provided a good test of our ability to forecast meteor activity outside of Earth orbit.”

Many readers have wondered if the outburst has anything to do with Comet 21P/Giacobini-Zinner’s close approach to Earth last month. “No,” says Cooke.  “The models show the outburst experienced at Earth was mainly caused by material ejected from the comet from 1945 to the mid 1960’s. The meteoroids were more than half a century old.”

Realtime Meteor Photo Gallery

Rock Comet Approaches Earth

Dec. 11, 2017: You’ve heard of comets. But have you ever heard of a rock comet? They exist, and a big one is approaching Earth this week. 3200 Phaethon will fly past our planet on Dec. 16th only 10 million km away. Measuring 5 km in diameter, this strange object is large enough for amateur astronomers to photograph through backyard telescopes. A few nights ago, the Astronomy Club of the Sing Yin Secondary School in Hong Kong video-recorded 3200 Phaethon’s approach using a 4-inch refractor:

“We observed 3200 Phaethon from the basketball court of our school campus,” the club reports. “Our school is located close to the city center where the visual limiting magnitude is about 2 to 3. Despite the glare, we were able to record the motion of this object.” (For others who wish to do this, Bob King of Sky & Telescope has written an excellent set of observing tips.)

3200 Phaethon is the source of the annual Gemini meteor shower, which is also coming this week. Sky watchers can see dozens of Geminids per hour on Dec. 13th and 14th as gravelly bits of the rock comet disintegrate in Earth’s upper atmosphere. The best time to look is during the dark hours before sunrise when Gemini is high in the sky.

“This is 3200 Phaethon’s closest encounter with Earth until December of 2093, when it will come to within 1.8 million miles,” notes Bill Cooke of NASA’s Meteoroid Environment Office. Despite the proximity of the rock comet, he doesn’t expect to see any extra Geminids this year. “It would take at least another revolution around the sun before new material from this flyby could encounter Earth – probably longer.”

A “rock comet” is an asteroid that comes very close to the sun–so close that solar heating scorches plumes of dust right off its stony surface. 3200 Phaethon comes extremely close to the sun, only 0.14 AU away, less than half the distance of Mercury, making it so hot that lead could flow like water across its sun-blasted surface. Astronomers believe that 3200 Phaethon might occasionally grow a comet-like tail of gravelly debris–raw material for the Geminid meteor shower. Indeed, NASA STEREO-A spacecraft may have seen this happening in 2010. There is much to learn about 32900 Phaethon, which is why NASA radars will be pinging it as it passes by. Stay tuned for updates.

Perseid Meteor Outburst

Every year in August, Earth passes through a stream of debris from Comet Swift-Tuttle, source of the annual Perseid meteor shower. The shower is beloved by sky watchers. It is rich in fireballs and plays out over a two-week period of warm, starry summer nights.

This year’s display is going to be even better than usual. “Our models predict an outburst on Aug. 11-12 with peak rates greater than 200 meteors/hour under ideally dark skies,” explains Bill Cooke of NASA’s Meteoroid Environment Office. “That’s about twice as many Perseids as usual.”


Perseids in Aug. 2015, a composite image by Petr Horalek of Kolonica, Slovakia [more]

In ordinary years, Earth grazes the edge of Swift-Tuttle’s debris zone. Occasionally, though, Jupiter’s gravity tugs the huge network of dust trails closer, and Earth plows through closer to the middle. This appears to be one of those years. Experts at NASA and elsewhere agree that three or more streams are on a collision course with Earth–hence the outburst.

Observing tips: Go outside between midnight and dawn on the morning of Aug. 12th. Allow about 45 minutes for your eyes to adjust to the dark. Lie on your back and look straight up. Perseids can appear anywhere in the sky, but their tails will point back to a single point in the constellation Perseus: sky map. Increased activity may also be seen on the morning of Aug. 13th.

Got clouds? NASA is planning a live broadcast of the Perseid meteor shower overnight on Aug. 11-12 and Aug. 12-13, beginning at 10 p.m. EDT. You can also listen to radar echoes from the Perseids on Space Weather Radio. More webcasts: from Israel, from Alabama.

Realtime Perseid Photo Gallery

Green Comet Approaches Earth

On March 21st, Comet 252P/LINEAR will make a close approach to Earth–only 0.036 AU (5.4 million km) away. This is the fifth closest cometary approach on record and, as a result, the normally dim comet has become an easy target for backyard telescopes. Indeed, it is brightening much faster than expected.

“Comet 252P/LINEAR has surpassed expectations and is now bordering on naked eye visibility for southern observers,” reports Michael Mattiazzo of Swan Hill, Australia. “At the moment it is near magnitude +6,” Observing from Brisbane, Australia, Tom Harradine didn’t even need a telescope to photograph 252P/LINEAR. On March 17th, he caught the green comet (circled) passing by the Tarantula Nebula using just a digital camera:

“This image is a stack of 140 four second exposures I made using a Canon EOS 70D set at f/4.0, ISO 12800, and 200mm,” he says.

The comet is green because its vaporizing nucleus emits diatomic carbon, C2, a gas which glows green in the near-vacuum of space. The verdant color will become more intense in the nights ahead as 252P/LINEAR approaches Earth.

In recent days, astronomers have realized that Comet 252P/LINEAR might have a companion. A smaller and much dimmer comet named “P/2016 BA14” will buzz Earth even closer than 252P/LINEAR on March 22nd. P/2016 BA14 appears to be a fragment of 252P/LINEAR. Unlike its parent, however, P/2016 BA14 is “pitifully faint” and difficult to observe. Sky and Telescope has the full story.

There is a chance that the comet’s approach could cause a minor meteor shower. According to the International Meteor Organization, “[modeling by forecaster] Mikhail Maslov indicates that there might be a weak episode of faint, very slow meteors (15.5 km/s) on March 28–30 from a radiant near the star μ Leporis.” Little is known about meteors from this comet, so estimates of the meteor rate are very uncertain. Maslov’s models suggest no more than 5 to 10 per hour.

This is a southern hemisphere event. At closest approach on March 21st, 252P/LINEAR will speed through the constellations Triangulum Australis and Apus, far south of the celestial equator. Observers can use this ephemeris to point their cameras and telescopes.

Meteor Balloon in the Stratosphere

When the Geminid meteor shower peaked on Dec. 14th, a snowstorm was in progress over the mountains of central California. No stars? No problem. Using a helium balloon, the students of Earth to Sky Calculus launched a low-light camera to photograph the shower high above the obscuring clouds. Their experimental payload ascended to 91,000 feet where the night sky looked like this:

The big white object at the top of the frame is the balloon, surrounded by some of the bright stars and planets of the pre-dawn sky. From the lower stratosphere, the freezing camera was able to see stars as dim as 2nd magnitude. This wasn’t as sensitive as the students had hoped, but it was good enough to record several Geminid fireballs. Here are a couple of movies showing Geminids emerging from behind the balloon: fireball #1, fireball #2. In the movies, stars and planets move in a lazy circle around the balloon–a result of the payload’s gentle spin–while Geminids streak in straight lines. The camera also recorded the balloon exploding at the apex of the flight, and the payload parachuting back to Earth.

The students plan to observe more meteor showers in the future with even better results. They believe they can boost the sensitivity of the camera by, e.g., warming the payload bay during the flight and improving the camera’s focus, pre-launch. If their improvements succeed, they could establish ballooning as a practical and fun way to monitor meteor showers in all kinds of weather. Stay tuned for updates.