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Northern Sky: January 5-18, 2019

Deane Morrison's "Northern Sky"  -  January 5 - 18, 2019

 
Early and mid-January are great times for star watching because skies are dark, and the winter constellations are bright. It may get a little nippy, but you don’t have to be outside very early, very late, or very long to see the main features.
 
The morning sky is especially good right now because the sun is rising about as late as it ever does. In the southeast, Venus and Jupiter are drawing closer every day, getting ready to pass each other on the 22nd. Venus is the brighter and, for now, the higher of the two. And to complete the predawn picture, the bright red star Antares, the heart of Scorpius, is just to the west of Jupiter.
 
In the evening, the winter constellations are up in the southeast after nightfall. They’re grouped pretty close together, so if you’re not familiar with them, you really should have a star chart to sort them out. But the most recognizable constellation, Orion, is easy to find because of the three stars that form his belt. 
 
Hanging from Orion’s belt is a line of stars that represent his sword. About halfway down the sword, binoculars will give you a glimpse of the sprawling and colorful Orion Nebula. The Orion Nebula is an immense cloud of gas and dust where new stars are forming. It’s about 1300 light-years away, and an estimated 24 light-years wide. Orion is also home to the famous Horsehead Nebula, which you need a telescope to see. But you can find lots of images of the Horsehead Nebula, and the Orion Nebula, online.
 
Orion’s left foot is Rigel, a blue-white star. Rigel and Betelgeuse, the red star at Orion’s right shoulder, are the brightest stars in Orion and among the top 10 in the whole sky. Rigel is a multiple star system, and overall, it’s estimated to be 40,000 times brighter than the sun. Betelgeuse is a gigantic star, estimated at 1,000 times the width of the sun. It’s less than 10 million years old—a mere child—but it’s aged rapidly and is now close to the end of its life. It’s expected to die in a spectacular supernova explosion. That may not happen for a million years, or it could blow up tomorrow.
 
In astronomy news, on New Year’s Day NASA announced that its New Horizons spacecraft, which gained fame by sending back stunning images from Pluto, has just completed what its principal investigator calls “the farthest exploration in the history of humankind.” It performed a flyby of an object in the Kuiper Belt, a doughnut-shaped ring of icy worlds beyond the orbit of Neptune. The object is called Ultima Thule, and it’s 4 billion miles away. The first pictures have just been released, and Ultima Thule looks, in the words of mission scientists, like a reddish snowman, something they’re now sure is the result of two spherical bodies that came together and stuck. Mission headquarters at Johns Hopkins University’s Applied Physics Laboratory says, “the two spheres likely joined as early as 99 percent of the way back to the formation of the solar system, colliding no faster than two cars in a fender bender.”
 
Ultima Thule is 19 miles long, and its two spheres are 12 and 9 miles wide. Scientists hope this object will clear up some mysteries about how our solar system formed. They want to know, for example, how small objects came together to form larger ones, and how they’ve been bombarded by meteor-like objects, although no impact craters are obvious on Ultima Thule.
 
Mark your calendars for Sunday, January 20th, when we’ll have a total eclipse of the moon. The show starts at 9:34 p.m., and I’ll have more on that in the next broadcast. 

Deane is a science writer at the University of Minnesota.
She authors the Minnesota Starwatch column which can be found on the University of Minnesota website at astro.umn.edu.
 

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