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Planet 9 January 21, 2016

Posted by aquillam in Astronomy, MichiganAstro.
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In case you missed it earlier this week, Caltech researchers Konstantin Batygin and Mike Brown think they’ve found a large planet in the Kuiper belt.

With a mass 10 times greater than Earth’s mass, it falls into that region of super Earth to Neptune sized planets. Regardless of whether it is a big terrestrial planet size or small gas giant size, it’s certainly big enough to have cleared its orbit, so it’s definitely a planet (though way out there, it’s probably not a terrestrial or jovian.)

It “orbits about 20 times farther from the sun on average than does Neptune.” Neptune is about 30 times farther from the Sun than Earth. That puts Planet Nine out at about 600 astronomical units! That is so far out, that the sun looks like nothing more than a bright star. And those planets we can see in our morning sky right now? An observer on Planet Nine wouldn’t be able to make them out all because they’re too close to the sun.

Here is a simulation of the sun and sky from Planet Nine using Starry Night software.


A simulation of the Sun and Solar System from 600 AU.

View all the naked eye planets at dawn January 20, 2016

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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The return of Mercury to the morning skies means all the naked eye planets are visible at dawn now. We have a couple weeks’ worth of great morning observing coming up, which might make you glad for late sunrises.

Start with January 24th. At 7 AM, Mercury, Venus, Saturn, Mars, Jupiter, and the Moon spread out across the entire sky.


The sky at 7 AM on January 24

The 25th marks the day of least span. From Mercury to Jupiter will cover only 112º 3′ that day, or about 2/3 of the sky from southeast to southwest.

By the 28th, the planets will have spread out to 112º 40’ (not a noticeable change to most of us), but the Moon will be inside that span. It’ll be right next to bright Jupiter, so if you like taking pictures, it’s a good opportunity.


The sky at 7 AM on January 28. Jupiter and the Moon make a good pair.

The Moon tends to overwhelm the other planets, but if you like conjunctions, look for the Moon and:  Spica on the 30th; Mars on February 1; Saturn on the 3rd; and Venus and Mercury on the 6th.

If your goal is a glimpse of illusive Mercury, take your binoculars out on February 4th, when Mercury is more than 5 1/2° above the southeast horizon at 7 AM. That’s about the same as holding 3 fingers at arm’s length, so a clear horizon is a must.  It’ll be up 10° by 7:30, but by then it will also be very bright out. 


Mercury is farthest from the horizon at 7 AM on February 4th.

On February 6, head out with the binoculars again and use Venus to find Mercury and an old crescent Moon. 


Bright Venus can guide you to an old Moon and Mercury on Feb. 6th.

Mercury, the fleet footed messenger, and Venus, goddess of love, will be at their closest on February 14, just in time for Valentine’s Day. May he speed your messages to the one you love.


The Moon Occults Aldebaran January 19, 2016

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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If it’s clear where you are this evening, head outside around 8:45 PM and look for the Moon. Nearby, you’ll spot Aldebaran, the bull’s eye. Keep watching! Aldebaran will disappear behind the Moon right around 9 PM! The dark side approaches first, so it can be a bit tricky to see it disappear.

The star will reappear around 10:20 – 10:30.


Simulation of 8:45 PM in Ann Arbor

Comet Catalina’s closest point to Earth January 9, 2016

Posted by aquillam in Astronomy, MichiganAstro.
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This coming week, Comet Catalina will be at its closest to Earth. Unfortunately, it’s only about a magnitude 6, so you’ll need a ‘scope if you want to see it. Also, if you’re in the southern hemisphere, you won’t be able to see it. For those up us up north, it’s skimming right along the handle of the Big Dipper, so at least it’s easy to find! Maps and more details from EarthSky.

Comet Catalina’s closest point to Earth | Human World | EarthSky


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