Ephemeris: 04/23/2024 – We are awaiting a bright nova

This is Bob Moler with Ephemeris for Tuesday, April 23rd. Today the Sun will be up for 13 hours and 54 minutes, setting at 8:38, and it will rise tomorrow at 6:42. The Moon, at full today, will rise at 8:40 this evening.

There is an event rarer than the appearance of Halley’s Comet. It’s an explosion of a star called T Coronae Borealis which means it’s in the constellation of the Northern Crown. Corona is a semicircle of stars located left of the bright star Arcturus, pointed to by the handle of the Big Dipper. The letter T means that it’s a variable star. It is something called a cataclysmic variable, or recurrent nova, and it blows up about every 80 years. The last time it did this was in 1946. Its brightness dips about 11 months before it goes kablooey. That dip has already happened. The star doesn’t destroy itself. It’s actually a white dwarf that’s siphoning off gases from a red giant star that it’s orbiting. When enough hydrogen gets accumulated, it ignites.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

The T Coronae Borealis finder animation for 10 pm tonight, in four frames. The 1st shows constellation outlines and labels. The 2nd frame shows the stars as they would appear in the sky without labels or lines. The 3rd frame shows the sky with the Nova T Corona Borealis. The 4th frame labels T Corona Borealis as T CrB. Created using Stellarium, LibreOffice Draw, and GIMP.