The Night Sky’s Two Brightest Stars

The two brightest stars in the night sky shine in the southern sky.

Here are Sirius (at right) and Canopus (at bottom left), the brightest and second brightest stars in the night sky, together near the southern Milky Way.

My image also captures the huge loops of the Gum Nebula, thought to be the remains of a supernova that blew up a million years ago. It’s utterly invisible to the naked eye, but Sirius and Canopus stand out as brilliant stars even from light polluted sites.

Sirius can be seen from northern latitudes but Canopus is below the horizon for any location north of 37° North or so. I shot this image from Australia where these stars pass overhead.

Sirius is a hot blue-white star 8.6 light years away. Canopus appears slightly dimmer but only because it lies much farther away, at some 310 light years. In reality it is a supergiant yellow-white star that shines with a luminosity 15,000 times that of our Sun.

This image takes in Canopus at bottom right, next to the Large Magellanic Cloud, and with the southern Milky Way sweeping across the top, with the Carina Nebula and its attendant star clusters at top left and parts of the Gum Nebula at right.

Here are a few cocktail party facts about Canopus:

• In 480,000 years its motion around the Galaxy will bring Canopus close enough to Earth that it will become the brightest star in our night sky, outranking Sirius.

• The origin of its name is a mystery. One idea is that the star is named for the pilot of the ship that took Menelaus to Troy on the quest to re-capture Helen.

• Canopus, the star, was used in ancient times as a key navigation star for those sailing to southern seas, as it would have risen above the southern horizon from latitudes below 35° North back around 2000 BCE.

• Today, Canopus is charted as the brightest star in the constellation of Carina the Keel, part of the ancient constellation of Argo Navis, named for the ship sailed by Jason and the Argonauts.

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