Bob Moler's Ephemeris Blog

Ephemeris for Thursday, January 24th.  The sun will rise at 8:09.  It’ll be up for 9 hours and 31 minutes, setting at 5:40.   The moon, 2 days before full, will set at 6:48 tomorrow morning.

Sirius is the brightest night-time star and is located in the south at 9 p.m. below and a bit left of Orion the Hunter.  We’ve visited Sirius Tuesday.  But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. Its name is Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title.  The tiny star was suspected as far back as 1834 due to Sirius’ wavy path against the more distant stars.  Sirius and the Pup have 50 year orbits of each other.  The Pup was first seen by famed 19th century telescope maker Alvan Clark in 1862 while testing a new telescope.  The Pup was the first of a new class of stars to be discovered, white dwarfs.  The Pup, with the mass of the sun, is only the size of the earth.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Sirius A and B (near the diffraction spike to the lower left), A Hubble Space Telescope photograph. Credit NASA, ESA.

The Hubble Space Telescope has two mirrors to produce its main image.  The concave primary mirror, and a secondary mirror in front supported by 4 vanes called a spider.  Light passing these vanes are bent or diffracted causing bright stars to have these 4 spikes.  Most reflecting telescopes produce these diffraction spikes.