Well over 100 people in California, Nevada, Arizona and Oregon observed a fireball at 5:35 p.m. PST Dec. 19. This event was unusual not for the brightness of the fireball—similar to that of a crescent Moon—but for the persistent train left behind after the object ablated. This persistent train lasted for minutes (compared to the one second duration of the fireball) and was caused by sunlight reflecting off dust particles left behind by the meteoroid as it broke apart in Earth’s atmosphere. Upper atmosphere winds distorted the train over time, giving it a curvy, “corkscrew” appearance.
An analysis of the eyewitness accounts indicates that the meteor first became visible at an altitude of 48 miles over the Pacific Ocean some 50 miles west of the entrance to San Francisco Bay. Moving west of south at 63,000 miles per hour, it managed to survive only a second or so before ablating and breaking apart at an altitude of 34 miles above the ocean.
The second week of December heralds the beginning of the strongest meteor shower of the year – the Geminids. It’s a good time to bundle up, go outside and watch one of Mother Nature’s best sky shows!
The Geminids are active every December, when Earth passes through a massive trail of dusty debris shed by a weird, rocky object named 3200 Phaethon. The dust and grit burn up when they run into Earth’s atmosphere in a flurry of “shooting stars.”
Phaethon’s nature is debated. It’s either a near-Earth asteroid or an extinct comet, sometimes called a rock comet. There is another object – an Apollo asteroid named 2005 UD – that is in a dynamically similar orbit to Phaethon, prompting speculation that the two were once part of a larger body that split apart or collided with another asteroid.
Most shower meteors are shed by comets when their orbits take them into the inner Solar System, but the Geminids may be the debris from this long-ago breakup or collision event. When you consider that the Geminid meteor stream has more mass than any other meteor shower, including the Perseids, whatever happened back then must have been pretty spectacular.
So what do potential Geminid watchers need to do this year?
It’s pretty simple, actually. The nearly First Quarter Moon sets around 10:30 p.m. local time, so wait until then to go out – the light from the Moon washes out the fainter meteors, which are more numerous. Find the darkest place you can, and give your eyes about 30 minutes to adapt to the dark. Avoid looking at your cell phone, as it will mess up your night vision. Lie flat on your back and look straight up, taking in as much sky as possible. You will soon start to see Geminid meteors. As the night progresses, the Geminid rate will increase, hitting a theoretical maximum of about 100 per hour around 2 a.m.
Bear in mind, this rate is for a perfect observer under perfect skies with Gemini straight overhead. The actual number for folks out in the dark countryside will be slightly more than 1 per minute. Folks in suburbs will see fewer, 30 to 40 per hour depending on the lighting conditions. And those downtown in major cities will see practically nothing – even though the Geminids are rich in beautiful green fireballs, the lights of New York, San Francisco, or Atlanta will blot even them out. Dark clear skies are the most important ingredient in observing meteor showers.
And while you’re scanning the sky for Geminids, you might notice a small, faint “ghostly” green patch in the constellation of Taurus – that’s Comet 46P/Wirtanen, which will be making its closest approach to Earth (7 million miles) for the next 20 years. We are actually going to have a comet visible to the unaided eye this holiday season!
Comets are notoriously unpredictable beasts, but if Wirtanen continues to follow its current brightening trend, it may reach a peak magnitude of around +3 (about as bright as a star in the handle of the Little Dipper) a couple of days past the Geminid peak, on December 16. Binoculars or a small telescope are good for taking a peak at Wirtanen, so bring them along for your night of Geminid watching. A green comet to complement the green fireballs!
A bright fireball lit up skies over Michigan at 8:08 p.m. EST on Jan. 16, an event that was witnessed and reported by hundreds of observers, many who captured video of the bright flash.
Based on the latest data, the extremely bright streak of light in the sky was caused by a six-foot-wide space rock — a small asteroid. It entered Earth’s atmosphere somewhere over southeast Michigan at an estimated 36,000 mph and exploded in the sky with the force of about 10 tons of TNT. The blast wave felt at ground level was equivalent to a 2.0 magnitude earthquake.
The fireball was so bright that it was seen through clouds by our meteor camera located at Oberlin college in Ohio, about 120 miles away.
Events this size aren’t much of a concern. For comparison, the blast caused by an asteroid estimated to be around 65 feet across entering over Chelyabinsk, Russia, was equivalent to an explosion of about 500,000 tons of TNT and shattered windows in six towns and cities in 2013. Meteorites produced by fireballs like this have been known to damage house roofs and cars, but there has never been an instance of someone being killed by a falling meteorite in recorded history.
The Earth intercepts around 100 tons of meteoritic material each day, the vast majority are tiny particles a millimeter in diameter or smaller. These particles produce meteors are that are too faint to be seen in the daylight and often go unnoticed at night. Events like the one over Michigan are caused by a much rarer, meter-sized object. About 10 of these are seen over North America per year, and they often produce meteorites.
There are more than 400 eyewitness reports of the Jan. 16 meteor, primarily coming from Michigan. Reports also came from people in nearby states and Ontario, Canada, according to the American Meteor Society. Based on these accounts, we know that the fireball started about 60 miles above Highway 23 north of Brighton and travelled a little north of west towards Howell, breaking apart at an altitude of 15 miles. Doppler weather radar picked up the fragments as they fell through the lower parts of the atmosphere, landing in the fields between the township of Hamburg and Lakeland. One of the unusual things about this meteor is that it followed a nearly straight-down trajectory, with the entry angle being just 21 degrees off vertical. Normally, meteors follow a much more shallow trajectory and have a longer ground track as a result.
NASA’s Short-term Prediction Research and Transition Center reported that a space-based lightning detector called the Geostationary Lightning Mapper — “GLM” for short — observed the bright meteor from its location approximately 22,300 miles above Earth. The SPoRT team helps organizations like the National Weather Service use unique Earth observations to improve short-term forecasts.
GLM is an instrument on NOAA’s GOES-16 spacecraft, one of the nation’s most advanced geostationary weather satellites. Geostationary satellites circle Earth at the same speed our planet is turning, which lets them stay in a fixed position in the sky. In fact, GOES is short for Geostationary Operational Environmental Satellite. GLM detected the bright light from the fireball and located its exact position within minutes. The timely data quickly backed-up eyewitness reports, seismic data, Doppler radar, and infrasound detections of this event.
Much like the nation’s weather satellites help us make decisions that protect people and property on Earth, NASA’s Meteoroid Environment Office watches the skies to understand the meteoroid environment and the risks it poses to astronauts and spacecraft, which do not have the protection of Earth’s atmosphere. We also keep an eye out for bright meteors, so that we can help people understand that “bright light in the night sky.”
Enjoy a summer evening of sky watching as the annual Perseid meteor shower peaks on the night of August 12 through the morning of August 13. Join meteor experts from NASA’s Marshall Space Flight Center for live Ustream commentary during the shower. Perseid meteor rates can get as high as 100 per hour, with many fireballs visible in the night sky
How to View the Perseid meteor shower
The best opportunity to see the Perseid meteor shower is during the dark, pre-dawn hours of August 13. The Perseidss streak across the sky from many directions. For optimal viewing, find an open skyline, where you can view the horizon without obstructions, such as buildings or trees. Try to view the Perseids as far away from artificial lights as possible. The darker the sky, the better viewing experience you can have. Lie on the ground and look straight up. Remember, your eyes can take up to 30 minutes to adjust to the darkness, so allow plenty of time for your eyes to adjust.
About the Perseids
The Perseids have been observed for at least 2,000 years and are associated with the comet Swift-Tuttle, which orbits the sun once every 133 years. Every August, the Earth passes through a cloud of the comet’s debris. This debris field consists of bits of ice and dust — most over 1,000 years old — and burns up in Earth’s atmosphere to create one of the best meteor showers of the year. The Perseids can be seen all over the sky, but the best viewing opportunities will be across the northern hemisphere. Those with sharp eyes will see that the meteors radiate from the direction of the constellation Perseus.
NASA Ustream: Observe the Perseid Meteor Shower
On Aug. 12, NASA’s Marshall Space Flight Center in Huntsville, Alabama, will host a live Ustream broadcast about the Perseid meteor shower. The event will highlight the science behind the Perseids, as well as NASA research related to meteors and comets. The broadcast will air 9 p.m. CDT Aug. 12, to 1 a.m. CDT Aug. 13 on the following Ustream channel: http://www.ustream.tv/channel/nasa-msfc
Special guests will include meteor experts Dr. Bill Cooke, Danielle Moser and Rhiannon Blaauw, all of NASA’s Micrometeoroid Office, located at Marshall. They will provide on-air commentary, as well as answer questions online, using Marshall social media accounts. Also scheduled to join the broadcast, via telephone, are experts from NASA’s Johnson Space Center, in Houston; NASA’s Goddard Space Flight Center in Greenbelt, Maryland; the American Meteor Society; the SETI Institute in Mountain View, California; and others.
There are two methods to join the online conversation during the broadcast. NASA followers can tweet questions to “@NASA_Marshall” using the hashtag “#askNASA.” Followers may also post questions on the Marshall Facebook account, replying to the 9 p.m. Aug. 12 Perseid “Q&A” post at: https://www.facebook.com/nasamarshallcenter
Image of Comet Lovejoy taken Saturday, January 10, by Dr. Bill Cooke. Image is a 3 minute exposure using the iTelescope T3 refractor. At the time of this image, the comet was some 45 million miles from Earth.
Discovered in August of 2014, Comet Lovejoy is currently sweeping north through the constellation Taurus, bright enough to offer good binocular views. Glowing softly with a greenish hue, Comet Lovejoy passed closest to planet Earth on January 7, while its perihelion (closest point to the Sun) will be on January 30. Classed as a long period comet, it should return again … in about 8,000 years.
On Sunday evening, a bright fireball was reported by visual observers in Tennessee. Occurring about 7:22 PM Central, the meteor was detected by 4 of our All Sky cameras – those in Huntsville; Chickamauga, GA; Cartersville, GA; and Dahlonega, GA. The fireball was picked up at an altitude of 55 miles moving east of south at 52,000 miles per hour; it burned up at an altitude of 27 miles just south of Anniston, AL. This was not a Taurid, as the orbit indicates it is a fragment from a Jupiter family comet, which have an aphelion (furthest distance from the Sun) out near Jupiter. This particular piece of interplanetary debris was between 2-3 inches in diameter and weighed about 5 ounces.
The Marshall Meteoroid Environment office put together the plot below showing the distribution of end heights of Geminids seen with our fireball camera network. 85% of Geminids burn up 40 to 55 miles above Earth’s surface and 15% get below 40 miles altitude.
Geminids penetrate deeper into the atmosphere than the Perseids because they are moving slower (78,000 mph for the Geminids compared to 130,000 mph for the Perseids) and are made up of denser material, owing to the fact that the Geminid parent body is rocky asteroid 3200 Phaethon and the Perseid parent is a comet yielding more fragile material.
This video shows meteors captured by a wide-field camera at the NASA Marshall Space Flight Center on the night of December 12. There are 141 events; at least 77 of these are Geminids, based on their angular speed and direction of travel. Near the end of the movie, a couple of satellites are visible crossing the field of view.
For those of us sky watching for meteors , this means we have a good chance of viewing a Geminid meteor. Tonight, December 13, into the early morning of December 14 is the peak. Happy meteor watching!
There was a bright fireball visible over north Georgia, eastern Tennessee, and South Carolina at 7:02:36 PM EST last night. All 4 NASA meteor cameras in the SouthEast picked it up 48 miles above the town of Rossville, just south of Chattanooga, moving at 9 miles per second (32,400 mph) slightly north of east. The meteor appears to have ablated (“burned up”) at 23 miles altitude SW of of Ocoee, TN. Though unusual, it is unlikely that this object produced any noticeable meteorites on the ground.
Orbit indicates that this meteor was asteroidal in origin, with an aphelion (farthest point from the Sun) in the main asteroid belt between Mars and Jupiter.
Asteroid 433 Eros made a close approach to Earth the morning of January 31st coming within 0.17 AU (15 million miles) of our planet. In this set of images taken that morning, the bright moving dot near the center of the field is the 21 mile long Eros. Somewhere on that tiny point of light rests a United States spacecraft — Near Shoemaker — which touched down on the asteroid’s surface on February 12, 2001 after completing 230 orbits around Eros.
In the animation you will also notice over 20 streaks of light moving almost horizontally across the field of view. What we did not realize at the time of imaging was that Eros was at approximately the declination of geosynchronous communication satellites! These satellites are orbiting some 22,236 miles above the earth in the “Clark belt.” We were able to identify most of the satellites seen and found quite a variety.
Included in the video are Brazilian satellites (Brazilsat B2, Star One C2); American satellites (Galaxy 11); Canadian satellites (Nimiq 4, Anik F1); Venezuelan satellites (Venesat-1); weather satellites (GEOS 12); television satellites (DirecTV 1-R); radio satellites (XM 3, Sirius FM); and Internet satellites (WildBlue – 1).
The next full moon is known as the Cold Moon, the Long Night Moon, or the Moon Before Yule. The moon will be “opposite” the sun at 9:38 a.m. EST on Saturday, Dec. 10. The moon will appear full for about three days around this time, from the evening of Thursday, Dec. 8 through the morning — and possibly the evening — of Sunday, Dec. 11.
On Dec.10, the moon will be so “opposite” the sun from the Earth that it will pass through the shadow of the Earth. The Earth’s shadow will begin to reduce the amount of sunlight reaching the moon at about 6:34 a.m. EST, but the U.S. East Coast will not be able to tell that the moon appears dimmer before it sets at 7:08 a.m. EST. The full shadow of the Earth (called the umbra) does not start to fall on the moon until about 7:46 a.m. EST, well after the moon has set for the U.S. East Coast. Even for the U.S. West Coast, the eclipse will be near moonset, making this a difficult eclipse to view. The extended period with reduced sunlight, including 51 minutes in the full shadow of the Earth, presents a challenging environment for spacecraft at the moon (LRO, the twin GRAIL spacecraft) that rely upon sunlight for heat and solar power. Because the two ARTEMIS spacecraft are in highly elliptical orbits around the moon, it is not clear if or how they will be impacted.
Europeans call the December full moon the Moon before Yule. Yule is an old northern European winter festival that is now associated with Christmas. The Native American names for the full moon in December — as reported in the Farmer’s Almanac — are the Cold Moon or the Long Night Moon. The Cold Moon gets its name because December is the month when it really starts to get cold, although our coldest average temperatures are in January. The Long Night Moon gets its name because the full moon in December occurs near the solstice, which has the longest night of the year. The full moon takes a high trajectory across the sky because it is opposite to the low sun, so the moon will be above the horizon longer than at other times of the year.
A full moon over Earth, seen by astronaut Ron Garan from the International Space Station. (NASA)