The week of December 30 – January 5 takes us from Day 4 to Day 10. This week we will highlight Rima Hyginus (the Hyginus Rille), viewable on Thursday evening, and the Quadrantid meteor shower.

Rima Hyginus (the Hyginus Rille) on the moonnarrow diagonal shunt connects Ariadaeus to Rima Hyginus on the moonRima Hyginus: [NE/J10;] At the west end of the Ariadaeus rille there is a narrow diagonal shunt that connects Ariadaeus to Rima Hyginus. This new rille parallels Rima Ariadaeus for about 20 miles, then continues west until it encounters the small 6-mile crater Hyginus. At that precise point, it changes direction and veers northward toward Mare Vaporum. The fact that Hyginus crater is located precisely at the pivot point is a curiosity. Can this just be coincidence?

Rima Hyginus is 2.5 miles wide and is easily seen in very small telescopes. It is really made up of a line of linked craters which are best seen just northwest of the crater Hyginus. With good optics and steady seeing, you might be able to make some of these out even with a three-inch scope. Wood suggests that these are actually rimless collapse pits of internal origin and that the crater Hyginus (also rimless) might be one of their number. Can you see any of the individual craters, or does Rima Hyginus just look like a linear feature?


Is Betelgeuse Going Supernova?

The constellation Orion is one of the most recognizable patterns in the night sky. But if you’ve looked at Orion recently and thought something seemed off, you’re not wrong: The giant red star Betelgeuse, which marks the hunter’s right shoulder (top left star from our perspective), is dimming rapidly, prompting speculation that it is about to explode. (Supernovas are the largest explosions the universe has ever known since the Big Bang!)

Normally, Betelgeuse is among the 10 brightest stars in the sky. However, the red giant began dimming in October, and by mid-December, the star had faded so much it wasn’t even in the top 20 … If Betelgeuse explodes, it will cast shadows at night and be visible in broad daylight for several months, then it will disappear from our sight! However, there is no cause for alarm; for a supernova to cause serious damage on the Earth, it would have to be as close as 30 light years, and Betelgeuse is more than 400. If we are lucky enough for it to happen soon, once astronomers announce that Betelgeuse is going to go supernova, you should get to a clear northern sky and enjoy the show. (Keep in mind that if you actually see Betelgeuse go supernova, the star actually blew up during the Middle Ages, and light from the blast is just now reaching us.)

The Quadrantid Meteor Shower will peak on the night of January 3-4 (more precisely at 1:00 a.m. MST; the peak window lasts only a few hours). You can expect to see 50-100 meteors per hour from a dark site (or 25-50 per hour from suburban areas). The meteors will radiate from a point just north of Boötes (known by the old name of Quadrans Muralis, hence “Quadrantids”).


It is highly recommended that you get a copy of Sky and Telescope’s Field Map of the Moon, the very finest Moon map available for use at the telescope. It is available for $10.95 at and on Amazon. All features mentioned in this blog will be keyed to the grid on the Field Map and will look like this: Plato: [NW/D9]

Courtesy of Gray Photography of Corpus Christi, Texas
Lunar photos: NASA / USGS / BMDO / LROC / ASU / DLR / LOLA / Moon Globe. Used by permission

Andrew Planck
Rima Hyginus on the Moon and Is Betelgeuse Going Supernova?

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