Things That Streak Through The Sky And Go Boom In The Night

Contrails from three jets intersected to unintentionally create the letter 'A' in the sky yesterday. Photo: Bob King

Transcontinental jets used the sky as a chalkboard yesterday afternoon. Three planes moving along different paths left contrails that intersected to create at least two letters of the alphabet, parallel lines and a right triangle. The lesson happened about an hour before sunset when the trails stood in bold contrast against a deep blue sky.

Contrails are formed when warm water vapor in plane exhaust condenses into droplets or ice crystals in the chilly upper atmosphere. It’s analogous to seeing your breath on a cold day.

A brilliant Leonid fireball from November 2001. Credit:NASA/ Meteoroid Environment Office

That’s not all that’s been streaking through the sky lately. Earlier this week on the night of the 11th, an extremely bright fireball flashed across the sky around 8:50 p.m. CST over Jackson, Miss. It was witnessed by many observers across the South. NASA astronomer Bill Cooke of the Meteoroid Environment Office of Marshall Space Flight Center confirmed the sighting, reporting that a station in Canada that monitors infrasound – sounds below the level of human hearing – picked up the signal of the meteor an hour and 20 minutes after the flash. Infrasound is used to monitor big events at large distances like earthquakes, nuclear bomb tests and occasional meteors entering the atmosphere. Whales and other animals use it to communicate.

“The infrasound signal at ELFO (Elginfield Infrasound Array) lasted some 2.5 minutes, and the amplitude permits an estimate of the meteor’s energy at 40-80 tons of TNT. If we assume a speed of 15 kilometers per second, we can derive a mass of 171 kg or 376 pounds. Making a further assumption that the meteor was porous rock gives a size, or diameter, of 0.54 meters or 21 inches,” according to Cooke.

A map prepared by Jake Schaefer the meteor's possible track over the ground. The blue lines are the boundaries of the infrasound detection; the red dots are radar hits.

Here’s a video that shows the meteor flash recorded by a surveillance camera in Louisiana. Amateur meteorite hunter Jake Schaefer from the Los Angeles area has been studying Nexrad Doppler radar data used by meteorologists at the time of the fireball’s fall and found a couple ‘hits’ which might indicate that pieces survived to land as meteorites. His latest plots, based on radar data, surveillance cameras, sonic booms and eyewitness reports, show the meteor’s possible track over the ground southwest of Jackson. More details and videos can be seen on his blog as well as read more details. Check out NASA’s Fireballs archive, too for other recent meteor videos.

Exactly where it landed is unknown, but a ground track is a great place to start. Similar radar data was used to help pinpoint the ground track and hence potential landing sites for meteorite fragments from last spring’s Mifflin fall over southwestern Wisconsin. Using the data and eyewitness reports, hunters found nearly 8 lbs. of fresh, black-crusted meteorites. Let’s hope it happens again down South.

A sundiving "storm-comet" recorded by SOHO and first noticed by Polish comet hunter Michal Kusiak on Dec. 20, 2010. Click to see a video and learn more. Credit: SOHO/Karl Battams

Not only are meteorites falling to Earth with regularity, but the sun recently experienced a storm of comets. Scientists and online comet hunters have discovered 2000 comets (as of Dec. 26, 2010) in the space-based observatory’s images since it began operation in 1995. Most of these belong to the Kreutz family of comets called ‘sungrazers’. They’re believed to be fragments of a much larger comet seen in the 12th century that broke up during a close pass of the sun.

But something odd happened in late December last year. The usual rate of one comet showing up every few days octupled to 25 comets in 10 days:

“The storm began on Dec 13th and ended on the 22nd,” says Karl Battams
of the Naval Research Lab in Washington, DC. “During that time, the
Solar and Heliospheric Observatory (SOHO) detected 25 comets diving into
the sun. It was crazy!”

Sungrazers are seen regularly by SOHO as they first brighten, then break up and vaporize in the sun’s intense heat. Astronomers aren’t sure what to make of the ‘storm’, but the number of comets recorded by SOHO has risen from 69 in 1997 to 200 in 2010. Comet lovers are hoping that the increase could mean we’re due for a good-sized sungrazer that will survive the sun’s intense heat and appear as a brilliant object at dusk or dawn. No one knows when the next one is due, so it’s wait and see for now.

4 Responses

    1. astrobob

      Hey Tina, you bet I do. The last spectacular sungrazer was Comet McNaught in 2007. With a small telescope or binoculars, it was actually visible in daytime sky around 1 p.m.! The southern hemisphere got the best views when it flew by Earth later that month and February. Before that, Comet Ikeya-Seki, another sungrazer, was a spectacle at dawn. So yes, I think there will be another in our lifetimes.

  1. MR.T

    I come a little. Will not this be a thing called “chem trail” not a contrail?
     Such a trail is seen in the evidence every day, and it is in every day of the light blue sky, and there is not already the blue sky to the utmost whether the sky is the white sky.
     I search an image, an animation in chem trail and am happy if reference can have “chem trail / . you understand the scatter of each place.
     In the situation that major mass communication cannot but report in U.S.A., Germany in Japan soon.
     It is a powder that the sky is whitish even if I have a look at a photograph-like feeling. Breath tends to scatter it for the night and day; will do; become it.
     Because Japan has only area of the State of American California degree, the surroundings scatter is possible with a jumbo jet. Therefore it is witnessed in the place considered to be the country.
    In addition, I keep scattering it because it does not come out on a cloudy day. The people to notice decrease in the time of the rainy season (the pivot is to scatter it every day).
    The scatter spreads by night, and it is often that the sky is white from the beginning in the morning recently.

    sorry,I can’t speak English so well

    1. astrobob

      Hi Mr. T – thank you for your e-mail. This is definitely a contrail. As far as I can tell, chem trails are yet another conspiracy theory similar to the completely false assertions that the U.S. never sent astronauts to the moon. I’ve seen hundreds of contrails, all of them created by normal exhaust from high-flying aircraft.

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