Fwd: June noted for near-Earth asteroids

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: June 7, 2013 8:43:56 AM GMT-06:00
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: June noted for near-Earth asteroids

 

 

      Jun. 6, 2013 4:56 PM 

Bernie Badger: June noted for near-Earth asteroids

NASA: What's Up for June: Asteroids, planets and rare meteor showers, oh my! June skies alight with stellar happenings. NASA video

 

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This image provided by NASA/JPL-Caltech shows a simulation of asteroid 2012 DA14 approaching from the south as it passes through the Earth-moon system on Feb. 15, 2013. / AP

Venus and Mercury have spread out as far as they are going to this time around. Now, Mercury has reversed course and will be heading back toward the sun while Venus continues to distance itself from the sun. Jupiter may still be visible, but it is fast slipping into brighter twilight as the days go by.

Sometimes, an asteroid will go by. Recently, asteroid 1998 QE2 received a lot of media attention because of its combination of large size and relative nearness. But there are many more asteroids coming near the Earth.

Asteroid	Date	Miss Distance	Size
1998 QE2	May 31	15.2 LD	1.6 km
2009 FE	June 4	9.6 LD	230 m
2000 FM10	June 5	50.3 LD	1.3 km
2002 KL3	June 6	66.4 LD	1.1 km
1999 WC2	June 12	39.2 LD	1.9 km
2006 RO36	June 18	70.9 LD	1.2 km

The LD stands for Lunar Distance, the average distance to the moon. I extracted the rows in the above table from spaceweather.com, which has a more complete list. Any of these objects would produce a devastating impact equivalent of millions of atomic weapons exploding at the same time.

Asteroid 1998 QE2 was near enough to perform synthetic radar imaging. Looking a bit like an ultrasound image, the radar image clearly showed a second object, a moon orbiting around 1998 QE2. The moon is close to the size of asteroid 2009 FE and would make a catastrophic impact all by itself.

Asteroid designations are constructed from a combination of the year of discovery and an alphabetic code for the half-month plus a letter indicating order of discovery. If more than 25 asteroids were discovered, the final letter receives a "re-use" subscript, starting with 1 for the first re-use (i.e., the second occurrence). For pragmatic reasons, the subscript is often rendered just as regular digits. Thus, 1998 QE2 and 1998 QE2 are both used to designate the same asteroid. In "packed" form, it would be 1998Q02E, which makes the symbol sortable from most-significant to least-significant "digits."

All of the asteroids above have well-known orbits that will not threaten the Earth any time soon. When a new asteroid is discovered, there are larger uncertainties in its path.  This may put the Earth within the error bounds. Over time, its velocity is better determined and the path is more predictable. When civilization is in the balance, or even our survival as a species, we want to be very sure where it will go.

There is only one asteroid that was detected in advance and impacted the Earth. This was 2008 TC3 that entered Earth's atmosphere on Oct. 7, 2008. It exploded at 23 miles above the Nubian Desert in Sudan. Although the asteroid was about 13 feet in diameter, weighing about 80 tons, only about 23 pounds of meteorites were collected. Unusually, 2008 TC3 contains nanodiamonds.

At the planetarium

The Astronaut Memorial Planetarium is open to the public Friday and Saturday evenings. At 7 p.m., the "Ring World" planetarium show explores the most photogenic planet, Saturn. At 8:15 p.m., see the IMAX movie "The Living Sea." Perennial favorite Pink Floyd provides the sonic textures of "Dark Side of the Moon" at the 9 p.m. laser show.

The planetarium is at the rear of the Cocoa branch campus of Brevard Community College. Call the box office at 321-433-7373 to inquire about schedule details and ticket prices. Check out brevardcc.edu/planet online for schedules, show descriptions and observing tools, including the full schedule.

The BCC observatory is open for public viewing from 6:45 p.m. to about 10:15 p.m. Fridays and Saturdays. There is no charge to look through the telescope, but donations are accepted. Saturn is up all night. The rings of Saturn are wide open now, giving one of the most memorable views you'll see through a telescope.

Badger is project coordinator at the Astronaut Memorial Planetarium in Cocoa. Send questions, suggestions, or comments to badgerb@brevardcc.edu.

 

Copyright © 2013 www.floridatoday.com. All rights reserved. 

 

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June Arietids – The Invisible Meteor Shower You Just Might See

by Bob King on June 6, 2013

 

You might just see a few meteors from the combined Arietids and Zeta Perseid showers that peak Friday and Saturday mornings. This map shows the sky facing northeast at dawn for the mid-section of the U.S. Created with Stellarium

I've never seen an Arietid meteor and chances are you haven't either. Peaking on June 7-8, the Arietid (AIR-ee-uh-tid) meteor shower is one of the strongest of the year with a maximum rate of 50-80 per hour. But there's a rub. The shower radiant, the point in the sky from which the meteors appear to radiate, is near the sun and best seen during daylight hours. When was the last time you saw meteors in daylight?

Early scientific exploration of the sky in radio waves at Jodrell Bank Observatory in 1945. Credit: Jodrell Bank, University of Manchester

If you're wondering how anyone could discover a meteor shower when the sun is out, it's impossible unless your eyes can see radio waves. The Arietids were first "seen" in 1947 by operators of radio equipment at Jodrell Bank Observatory in England. Meteors leave trails of ionized gases when they rip through our upper atmosphere at tens of thousands of miles per hour and briefly make ideal reflectors of radio waves.

You can even hear them yourself by tuning to a "blank" spot between stations on an FM radio and listening for sudden bursts of talk or music when the meteor trail boosts a neighboring station into audibility. Click HERE for simple instructions if you'd like to give it a try.

The Arietids are joined by a second daytime shower at the same time by the Zeta Perseids, a smaller shower, to guarantee a couple busy days of meteor-listening — and potential meteor-watching —  on and around June 7-8. Most meteor showers are tied to a particular comet, since they're swarms of dusty detritus left behind in a comet's wake as it travels 'round the sun. When Earth intersects the stream, tiny comet bits slam into the atmosphere, heat up to 3,000 F or more and self-immolate in glowing streaks we call meteors. Occasionally a shower's parent can be an asteroid as in the case of the January Quadrantid meteor shower. It's suspected that the asteroid 2003 EH1 may be a extinct comet.

Most meteors are comet dust striking at the atmosphere at speeds so high, they vaporiz in a blaze of light. This is a meteor from the Leonid shower in 2001. Credit: Bob King

No one's certain of the Arietids' parentage. Likely candidates include the near-Earth asteroid 1566 Icarus and Comet 96P/Machholz, both of which have orbits that resemble the shower's.

After ignoring May's Eta Aquarid meteor shower for years because of its very low radiant at dawn, I was pleasantly surprised by the many meteors I saw when I happened to catch the shower at maximum on May 6 this year. Circumstances are only slightly worse for the Arietids. That's why I think it's worth your while to check out this shower tomorrow (Friday) and Saturday morning(June 7-8). Face east and start watching an hour or two before the start of dawn and continue your vigil until the sky brightens in the east.

The lesser Zeta Perseids are also active, adding to the fun. Since the two shower radiants are close to each other in the sky, it may be hard to tell which you're seeing. No matter. Any fiery streaks you can trace back toward the east-northeast horizon will likely be one or the other.

Earth-grazing meteor photographed by Manuel Conde of Barcelona, Spain.

Whenever a radiant is near the horizon, many of the meteors approaching us do so at a very shallow angle almost horizontal to the Earth's atmosphere. From our perspective they travel slowly and last a much longer time than do meteors striking the air at a steeper angle, typical for radiants that are higher in the sky.

Astronomers use the poetic "Earth-grazers" to describe them. Having seen a handful of these unique beauties during the May Aquarid shower, I'm hungry for more. Since the Arietids / Zeta Perseids also originate low in the sky, we should expect similar sights Friday and Saturday mornings.

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