What are the signs of spring? They are as familiar as a blooming daffodil, a songbird at dawn, a surprising shaft of warmth from the afternoon sun. And, oh yes, don’t forget the meteors.
“Spring is fireball season,” says Bill Cooke of NASA’s Meteoroid Environment Center. “For reasons we don’t fully understand, the rate of bright meteors climbs during the weeks around the vernal equinox.”
In other seasons, a person willing to watch the sky from dusk to dawn could expect to see around 10 random or “sporadic” fireballs. A fireball is a meteor brighter than the planet Venus. Earth is bombarded by them as our planet plows through the jetsam and flotsam of space–i.e., fragments of broken asteroids and decaying comets that litter the inner solar system.
In spring, fireballs are more abundant. Their nightly rate mysteriously climbs 10% to 30%.
“We’ve known about this phenomenon for more than 30 years,” says Cooke. “It’s not only fireballs that are affected. Meteorite falls–space rocks that actually hit the ground–are more common in spring as well1.”
Researchers who study Earth’s meteoroid environment have never come up with a satisfactory explanation for the extra fireballs. In fact, the more they think about it, the stranger it gets…
Read the Science@NASA article here:
Watching the skies is much more than a hobby with the Marshall Center’s Bill Cooke, lead of the Meteoroid Environment office — it’s an obsession.
Each morning when Cooke logs on to his computer, he quickly checks email for the daily update from the fireball camera network. Groups of smart cameras in Cooke’s new Fireball network triangulate the fireballs’ paths, and generate the report that appears in his email each morning.
Cooke’s network of cameras is currently made up of three cameras; however he is looking to add 12 additional cameras, and he’s actively seeking schools, science centers and planetariums to host his cameras. The cameras will need to be deployed in clusters of five. One group will be spread over the southeast United States; another in the Ohio and Kentucky area; and another along the Atlantic coast in the northeast. The hope is that at least one of the three regions will have clear skies at any given time.
The following criteria must be met for a location to be considered as a camera site:
- Location east of the Mississippi River
- Clear horizon — few trees
- Few bright lights — none close to camera
- Fast internet connection
Stay tuned for details on what the fireball network reports!
The 2010 solstice lunar eclipse is one for the books, but check out these images from two cameras in the Canadian all-sky meteor camera network.These cameras are similar to the ones used for observation at NASA’s Marshall Space Flight Center: all-sky, black-and-white, and detecting bright meteors, or fireballs. Below are two stacked images of the eclipse:
Stacked image of the eclipse using images taken every five minutes from McMaster University
between 6:32 and 9:32 UT.
A similarly stacked image, combining pictures every five minutes between 5:27-9:37;
it was taken from Orangeville, ON, Canada.
Just as a reminder, the eclipse event timings in UT were:
- Partial begins: 6:33
- Total begins: 7:41
- Mid eclipse: 8:17
- Total ends: 8:53
- Partial ends: 10:01
So both cameras captured the full moon as it normally appears, then imaged it as it was eclipsed through the partial and total phases. Unfortunately, bad weather rolled in before the eclipse ended!
The Canadian cameras also detected meteors during the eclipse. Here are a few good ones:
The following two images were also taken from McMaster and Orangeville at about 7:38 UT, just before the total eclipse began, but after the partial eclipse had started. These pictures show an image of a meteor fairly close to the moon in the field of view.
The following three images were recorded from Elginfield, ON, Canada, McMaster, and Orangeville, respectively, at about 9:00 UT, just after the total eclipse phase ended, but before the partial eclipse ended. This meteor ablated by a height of 83 kilometers, or 52 miles.
Images courtesy of the Meteor Physics Group at the University of Western Ontario in London, ON, Canada
Text courtesy of Danielle Moser, NASA’s Marshall Space Flight Center, Meteoroid Environment Office
Last night the NASA All-sky Meteor cameras detected their first Geminid fireball of 2010! The fireball, detected from cameras positioned in both Huntsville, Ala., and Chickamauga, Ga., was first spotted over southern Tennessee at a height of 58.7 miles above the ground. It streaked across the sky over northern Alabama at a speed of 76,300 mph and completely burned up by a height of 53.4 miles. If the weather remains clear, we should be in for a good Geminid show this year!
Geminid fireball meteor seen from Huntsville (left) and Chickamauga (right) on December 6, 2010.
Meteor rates should peak early next week, so stay tuned for more news about the Geminid meteor shower!
Image courtesy of Danielle Moser, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.
It was brief, but it was brilliant! On Saturday, Oct. 2, 2010 at approximately 8:50 p.m. CDT, cameras operated by NASA’s Meteoroid Environment Office at Marshall Space Flight Center in Huntsville, Ala., recorded a slow moving fireball moving from the north to the southwest.
Enhanced-color image of Alabama fireball meteor.
The fireball was moving approximately 35,300 mph (15.8 km/s). It appeared at an altitude of 45.5 miles (73.2 km) and ablated, or burned up, at an altitude of 25.3 miles (40.7 km). The meteor experienced significant deceleration as it entered the atmosphere, resulting in a meteor trail that lasted about three seconds, seen in the movie below:
Using data from cameras at both Huntsville and Chickamauga, Ga., astronomers at the Marshall Center determined that the meteor was located over Marion County, Ala.
Diagram of fireball’s path over Marion County, Ala.
Images and video courtesy of Danielle Moser, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.
Marshall Space Flight Center PAO Steve Roy was out jogging early Friday morning with his dogs, Lilly and Scout, when he couldn’t help but notice this bright meteor low in the eastern sky.
Also seen by NASA’s all sky meteor cameras at MSFC and in Chickamauga, GA, the meteor was located above the Atlanta area, some 180 miles away from where he was running.
Moving at 97,500 miles per hour, it disintegrated in a flash of light 45 miles above the ground. You can watch the meteor as captured by the cameras at the Marshall Space Flight Center:
and also as seen by the camera at Chickamauga:
Images/movies courtesy of Bill Cooke, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.
I am asked this question over and over again, and it’s a good one. Everyone knows that you have to be in the right place to observe solar eclipses and other astronomical goings-on, so why should meteor showers be any different?
You do have to be in the right part of the planet to view meteor outbursts or storms, because the trails of comet debris are so narrow (hundreds of thousands of miles) that it only takes a few hours for the Earth to pass through the stream. A few hours is not enough time for the Earth to do a complete rotation (which takes 24 hours), so only those people located in areas where it is night and where the radiant is visible will be able to see the outburst or storm. These dramatic events require the viewers to be in the right ranges of both latitude AND longitude.
This is not true for normal meteor showers, like this year’s Perseids. The main stream of particles extends for millions of miles along Earth’s orbit, requiring days for it to cross. All we need is one day to take the longitude out of the visibility calculations, because then the entire planet will experience night while the shower is still going on. That’s the good news.
The kicker is that we not only have to have darkness, but also the radiant — in this case, located in the constellation of Perseus — has to be visible, i.e. above the horizon. The elevation of the radiant depends in part on latitude of the observer, and one can derive — or look up, in this age of Google — a relatively simple equation that gives the maximum elevation of the radiant:
maximum elevation = 90 – |dec -lat|
where dec is the declination of the radiant and lat is latitude of the observer (all in degrees). The vertical lines before dec and after lat mean to take the absolute value of dec — lat. In order to see meteors from the shower, the maximum elevation must be 0 or greater (preferably more than 15 degrees). In the case of the Perseids, dec = 58 deg, so it is easy to calculate the maximum elevation for various latitudes:
We see that everyone in the northern hemisphere has a shot at seeing Perseids (weather permitting), but folks south of -32 degrees latitude get the shaft.
On the world map above, the red shaded area is the region where the Perseids will not be visible. If you live south of Brazil, at the very southern tip of Africa, or southern Austrailia, you need to take a road trip to the North if you wish to see Perseids. If you want see decent numbers, it will be a long ride, as you need to trek to somewhere above -17 degrees latitude.
So will I see Perseids? You can find out on your own — look up your latitude (remember, Google is your friend), use the equation above, stick in 58 degrees for the dec, and calculate the maximum elevation. If it is above 15 degrees, you are good.
Remember to get away from city lights. A dark sky is important.
Enjoy the show!