~ St. Maarten’s Backyard Astronomy for January 25 & 26 ~
Sun rises at 6:46am
Sun sets at 6:02pm
Lunar phase: new moon, waxing crescent
Moon rises: 7:22am, Saturday
Moon sets: 6:51pm, Saturday
The nights this weekend will give you a very dark sky because the moon will be virtually absent throughout the dark hours. This means you should have great star gazing. Let’s see if we can locate one of the longest and faintest constellations in the whole sky. It’s called Eridanus the River. Not so well known these days, but it was once very important to the cultural beliefs of the Ancient World.
In ancient Greece, back in the days of Homer’s Odyssey, Eridanus was thought to be the “River of the Ocean” and in their minds, it encircled a flat Earth. But actually, Eridanus could represent whatever nearby river was thought to bring life to the land. It is often associated with the Nile River in Egypt, the Euphrates River in Mesopotamia (western Asia), or the River Po in Italy. Eridanus is also sometimes called the River of Orion.
To find Eridanus the River, look first near the constellation Orion the Hunter, always easily located by his three-star belt. Look towards the star Rigel at Orion’s foot. Eridanus begins there and winds around the sky in a great loop, eventually finding its way down toward the southern horizon.
If you live in Europe or North America, the River disappears below the southern horizon, but since we live at a very southerly latitude here on St. Maarten, we can see the star that represents the end of the River. This star is named Achernar.
Achernar is very bright. You can see it just west of due south after sunset – 7:30pm is ideal viewing. By 8:30, you can see another bright star in the south, rising just east of due south. This is the bright beacon Canopus, used by sailors in the southern hemisphere for navigation, which is very cool because Canopus is in the constellation Carina, the sailboat!
By 9:00pm, you will say goodnight to Achernar as it slides under the southeastern horizon. For the rest of the night, Eridanus the River flows to the great beyond and Canopus takes over the southern sky. High above, the brilliant Sirius the Dog Star dominates.
Why search Eridanus the River? After all, it is such a faint constellation and few people today have ever even heard of it! Here are two reasons: (1) it’s a very beautiful constellation; (2) seeing Eridanus – understanding its association with a river in the minds of the early stargazers – can give you an appreciation of those early stargazers from centuries ago.
Thank you for keeping up with the Night Sky articles. If you are out later on in the week, each star rises about four minutes earlier each day than written here, and the moon rises 50 minutes later. Night Sky is researched and compiled by Lisa Davis-Burnett. Earthsky.org is a key resource for information and images. Questions or comments? Email This email address is being protected from spambots. You need JavaScript enabled to view it.
