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The Michigan Meteor and possible meteorites January 17, 2018

Posted by aquillam in Astronomy, MichiganAstro.
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Last night a rather large meteor exploded over Michigan. Stories and video are all over social media. The American Meteor Society website was down for a while, but it’s back up now, and they have a map where you can see where everyone who saw it was, and the probable ground path.
This was a bolide, a very bright meteor that explodes or breaks up, and usually makes it into the lower atmosphere. That makes it more likely that fragments may have made it to the ground.  So if you happen to live or own property near the ground path, you might want to go look for some fragments.
Some things to know:
If you suspect you might have an impact site, TAKE PICTURES BEFORE YOU TOUCH ANYTHING. Then, put something down for scale, like a quarter, or a rock hammer, and take a few more pictures. Then and only then, should you pick up and examine the rocks.
The glow of the meteor is mostly from the air around it. That will make the surface hot, but, like fried ice cream or baked Alaska, the inside will still be the icy cold of outer space. If you find a molten ball of goo, or something that looks like it was recently a molten ball of goo, it’s not a meteorite. This is slag, not a meteorite.


This is slag, not a meteorite. http://meteorites.wustl.edu/id/slagq_gil.jpg

If it’s a fragment of last night’s meteor, it won’t have weathered yet, so it should have a thin fusion crust, which should be dark.


This cross section shows the crust is fairly thin. It is also relatively smooth, but with a crackle-finish like texture. http://www.meteorite-recon.com/home/meteorite-documentaries/meteorite-fusion-crust

It came in at an angle, and probably broke into smaller pieces. Small pieces make small craters, but the snow here is rather fluffy. If small meteorites hit deeper snow, they may actually melt holes through it, and you’ll find the meteor stuck to the bottom of an ice core. In shallow snow over solid ground, you’re probably looking for fairly small dark rocks in shallow oblong craters maybe up to 10 times wider than the rock. The crater size varies dramatically though.
Very large meteorites can be valuable. Meteorites from events that were documented and witnessed (like this one) can be valuable. But don’t expect to buy a car by selling a couple small meteorites on eBay. Maybe a nice dinner at a fancy restaurant for your family. If you think you have a meteorite and are considering donating or loaning it to science, I’d suggest starting with NASA’s “Watch the Skies” site.

Elusive Mercury in the Evening December 1, 2017

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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This weekend promises amazing weather for December in SE Michigan. Take advantage of it by looking for the elusive planet Mercury!

Sunset on December 1 in A2 is at about 5:03 PM, and Mercury sets at about 6, so grab a pair of binoculars and go out between roughly 5:15 – 5:45 and look low in the SW. Be sure to check out Saturn too: it’ll disappear behind the Sun soon! The image below is for 5:30 on Friday December 1, 2017

As the days progress, Mercury gets closer to the Sun in the sky (yes, it’s in retrograde), so by the 5th or 6th it’ll be all but impossible to catch! Conjunction is on the 12th. Saturn conjunction is December 21. 01Dec1730SW_Mercury.png

Morning Planets Conjunction November 8, 2017

Posted by aquillam in Astronomy, MichiganAstro.
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Mother Nature provides a huge reward for early risers in the coming week. Venus and Jupiter will practically merge in the pre-dawn skies!

You’ll want a pair of binoculars or a small telescope when you head outside at around 7 AM on November 10 – 15. The more mornings you can look, the better!

Venus will be easy to spot, assuming you have a good horizon, low in the ESE. Pan around a bit to spot Jupiter nearby. They’re only a couple degrees apart on the 10th and 15th. Be sure to look for Mars and Spica while you’re out there.


Mars, Spica, Venus and Jupiter in the pre-dawn skies November 10

Between the 10th and 15th, Jupiter and Venus will close the gap. On the morning of November 13, you might need those binoculars to see that there are still two planets there! At minimum separation, they’re about a third of a degree apart. That’s less than the diameter of the Moon!


A crescent Moon, Mars, Spica, Jupiter, and Venus in the ESE before dawn on November 13. Venus and Jupiter are too close together to appear as separate objects in this map.

That’s about the time the Moon starts trying to join the group as well. If you’re up for a couple more mornings, you can watch the Moon slide past Mars on the 14th –  15, Jupiter and Venus on the 16th, and *maybe* catch the very old Moon on the 17th (it’s a tough observation though, and you’ll need a really good horizon!)


Mars, Spica, Jupiter, Venus, and a very tiny crescent Moon in the ESE before dawn on November 17.

The Moon and Aldebaran November 3, 2017

Posted by aquillam in Astronomy, MichiganAstro.
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The Moon will be full at 1:23 AM on November 4 in Ann Arbor. But November 5th is the day to watch it.

Get out a telescope or a pair of binoculars and head outside a little before 8 PM. Look in the direction of the Moon, but find Taurus, and the red star Aldebaran. Keep your eye on that star, because at about 3 minutes after 8 PM, it’ll disappear behind the Moon! (See a map of where it’s visible and local times for more places on the The International Occultation Timing Association website.)

If you miss the disappearance, you can try and catch the reappearance. It is best if you have a relatively wide field, so you can see most if not all of the Moon. The Moon moves west to east with respect to the stars, so you’ll want to watch the western edge of the Moon. Unfortunately, whether you should watch the top, middle, or bottom depends on where you’re observing from. In SE Michigan, Aldebaran should reappear from about the middle of the western edge at about 8:57 pm. Give yourself several minutes lead time to prepare, because it’s really easy to miss the moment of re-appearance!

If you miss this one, your next chance will come December 30.