An official website of the United States government
Here's how you know
A .mil website belongs to an official U.S. Department of Defense organization in the United States.
A lock (lock ) or https:// means you’ve safely connected to the .mil website. Share sensitive information only on official, secure websites.

The Lion of April

April 11, 2023 | By Geoff Chester

Venus and the Pleiades, 2017 April 5
Imaged with a 8-cm (3-inch) f/6 Antares Sentinel refractor and a Canon EOS Rebel T2i DSLR

The Moon begins the week along the southernmost reaches of the ecliptic, skirting the southern horizons among the stars of mid-summer.  Last Quarter occurs on the 13th at 5:11 am Eastern Daylight Time.  On the morning of the 12th you will find Luna in the middle of the “Teapot” asterism of Sagittarius.  If you are out and about before sunrise on the 16th look for yellow-hued Saturn about five degrees northwest of the crescent Moon low in the southeastern sky.

The April campaign for the citizen-science Globe at Night program begins this week and runs through the evening of the 21st.  This month’s target constellation is Leo, the Lion, which may be found crossing the meridian at 10:00 pm local time.  Leo consists of two asterisms, the brighter of which is popularly called “The Sickle”.  It is fairly easy to trace out above the constellation’s brightest star, Regulus, and resembles a “backwards” question mark.  This asterism forms the Lion’s head, while a right triangle of stars about 15 degrees to the east forms the feline’s hindquarters.  The constellation represents the Nemean Lion, a fearsome beast with a hide impervious to the weapons of mortals.  The Lion was eventually dispatched by Hercules as the first of his Twelve Labors.  Hercules then skinned the Lion’s hide with one of its claws and used it as armor for his remaining adventures.  It is one of the few constellations that actually resembles its namesake.

I can see the principal stars of Leo from my suburban yard, but he is much easier to spot if you are away from city lights.  Wherever you observe Leo from, your input is vital to the Globe at Night project.  Using their web app, match your view of Leo with the charts on the page and submit your observation.  Why is your input so valuable? Since its inception in 2009, well over 100,000 observations have documented the overall brightening of our skies due to artificial nighttime lighting.  At present, night sky brightness is increasing by about ten percent per year worldwide, but the trend can be reversed with public awareness of sensible lighting ordinances.

As Leo climbs toward the meridian, winter’s bright stars are heeling to the west and beginning to set.  By 10:30 pm you will find Orion low in the southwest, his bright blue star Rigel poised to set.  Looking back to Leo, now high in the south, turn to face north to locate the familiar Big Dipper asterism.  After Orion, the seven stars that make up the Dipper are probably the most recognized star pattern in the sky.  While most of us see the group as a giant ladle in the sky, it is also recognized as a plow or a wagon drawn by three horses.  If you look carefully at the middle star in the Dipper’s “handle”, you may notice a faint star snuggled up to the brighter star, Mizar.  The ability to see the fainter star, known as Alcor, was once used as a test to determine visual acuity for recruits into the Roman army.  Point a small telescope at Mizar and Alcor and you will find a surprise: Mizar itself is a double star.  Indeed, it was the first double star I found in a telescope a few decades ago.  The pair is quite easy to split in small instruments, but if you are looking for more of a challenge, swing back to Leo and look at the brightest star in Leo’s “mane” above Regulus.  This star, Algieba, splits into a close pair of gold-hued components and is one of the prettiest double stars in the sky.

Mercury reaches his greatest elongation east of the Sun on the 11th.  For most of the week he is about as high as he can get in the western twilight sky.  You will find the elusive planet about 10 degrees above the horizon half an hour after sunset.  He should be visible to the naked eye for the first couple of evenings, but by the weekend he will begin to fade, so you might want to use binoculars to spot him.

Venus starts the week just to the southeast of the Pleiades star cluster in Taurus.  Binoculars will give a nice view of the dazzling planet and the Seven Sisters, especially on the evenings of the 11th and 12th.  By the end of the week you will find her placed well north of the bright star Aldebaran.

Mars is continuing his eastward trek among the stars of Gemini.  You will find him between the bright star Betelgeuse in Orion and the Twin Stars of Gemini, Castor and Pollux.

Commander, Naval Meteorology and Oceanography Command | 1100 Balch Blvd. | Stennis Space Center, Mississippi 39529