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Observing tips for July 4th, 2018 July 2, 2018

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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The forth of July brings a lot of people outside after dark. While you’re waiting for those fireworks to begin, here are a few things to look for.

I recommend taking along a pair of binoculars.


Venus and Mercury in the West July 3, 2018, 9:30 PM.

Start about half an hour after sunset (or about 9:30 in SE Michigan) and look west. About 20º ( 2 sideways fists) above due west is Venus. As the skies darken, it stands out like a beacon! look 16º (index finger to pinky) down and to the right for Mercury. Mercury can be a tough object to spot because it’s never far from the Sun, so it’s never visible in really dark skies. The first map is for July 3, 9:30 PM in Ann Arbor, but should be good for the 4th as well.


Jupiter and Saturn in the south at 10 PM July 4

Fireworks usually begin around 10 PM (especially if you’re farther north.) Get a seat facing south for some of the summer’s best celestial show. Jupiter is about 30º above the southern horizon, and Saturn about 10º up in the SE. While you’re looking that way, be sure to check out Scorpio and Sagittarius too. Bright Antares, the heart of the scorpion, falls between Jupiter and Saturn right now.

With binoculars or a small telescope, you can pull in the 4 brightest moons of Jupiter. They’ll be lined up in a tight row on the 4th, which helps make it easier to pick them out at low magnification.

From left to right, Io, Europa, Jupiter, Ganymede, and Callisto

The Galilean Moons of Jupiter at 10 PM July 4, 2018.

If you actually have a small telescope and can pull your eye away from Jupiter, check out nearby Zubenelgenubi, a nice double star whose name means “southern claw” because it was once considered part of Scorpius.

Saturn is sitting on the top of the teapot. If your skies are dark enough later in the evening, you’ll be able to see the Milky Way trailing up the sky next to it. With binoculars or a small scope, the rings should be visible, if only as a strangely oblong shape. Some of the brighter moons may also be visible, though they aren’t nearly as easy as Jupiter’s moons.

From left to right, Iapetus, Rhea, Saturn, Tethys, and Titan, which is actually much lower that the other moons.

Saturn and its moons, July 4, 2018 at 10 pm

It’s early days yet for Mars, but if you’re out past midnight, look back to the same are Saturn was at 10 PM. Mars rises ESE around 11 PM, so it’s up nearly 10º in the SE at midnight. It’s the brightest thing in that area right now, and only getting brighter, so if your skies are clear, it’ll be hard to miss. Keep an eye on it the rest of the month as it moves toward closest approach on July 31!


News | Celebrate Pi Day, the NASA Way! March 8, 2018

Posted by aquillam in MichiganAstro, Science, teaching.
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I like pi, and I like space exploration, so I love Pi Day with NASA!

On March 14, JPL will celebrate Pi Day with the fifth annual “Pi in the Sky” illustrated math challenge, featuring pi-related space problems that you can do at home.

Source: News | Celebrate Pi Day, the NASA Way!

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