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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!

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February 15 solar eclipse February 12, 2018

Posted by aquillam in Astronomy.
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There’s a eclipse on February 15, 2018!

Unfortunately, it’s only a partial, and it’s best viewed from Antarctica.

But if you looking for an excuse to finish off the Valentine’s wine, you can raise a glass to the Sun the next afternoon. Or pull out your photo album and review those pictures from last August. Now THAT was an eclipse!

This is the second of two in this eclipse series. Hopefully you caught the super-blue-moon eclipse on January 31!  The next series starts with another partial solar eclipse over Australia in mid July, then another total lunar eclipse visible primarily from Africa & Asia. Guess it’ll be a while before it’s worth another eclipse post…

Super purple Moon! January 30, 2018

Posted by aquillam in Astronomy.
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It’s been about 6 months since the last set of eclipses, so its time for the next set, starting with tomorrow morning!

This first eclipse of the year will be a total lunar eclipse, visible primarily over the Pacific. Since the Earth’s atmosphere preferentially scatters blue light, Earth’s shadow tends to be fairly red in color, though the shade depends on a lot of other things, like the amount of smoke and ash from fires or volcanos suspended in the upper layers. As the Moon passes through the shadow, it takes on a reddish hue. For this reason a total lunar eclipse is often referred to as a blood moon.

The Moon can only pass through Earth’s shadow when the Moon, Earth and Sun are lined up, in that order. But that is also a full moon! So a lunar eclipse is automatically a full moon. A blue moon is the second full moon in a month, something that happens about once a year. This year’s blue Moon falls this month. Tomorrow in fact!

So, tomorrow’s blue moon is also a lunar eclipse. And what do you get if you put blue and red together? Purple!

But wait, there’s more!

Blue moons don’t happen very often, so we need something else to differentiate special Moons. How about when the full Moon is also at it’s closest point to Earth in its orbit? It will look a bit bigger than normal then, so we call that a super moon.

So tomorrow, be sure to check out the super purple Moon!

Alas here in Ann Arbor, it will probably set before it’s noticeably red… But you can watch it on NASA TV!

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.

slag

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.

meteorite-cross-section

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.