What’s Up in the Sky – March, 2019
We Should Bestow Awards on These Stars
In like a lion out like a lamb is usually a phrase that refers to the weather in March. But there’s also a connection to the constellation Leo, the lion, that will dominate the southern sky during the month of April. But as the winter constellations sink lower in the west, this is a good time to get one last look at them.
Facing the south an hour after sunset you can easily spot the prominent constellation Orion, the hunter. His two brightest stars represent his right shoulder (Betelgeuse) and left knee (Rigel). Betelgeuse is a red supergiant with a mass 10 to 15 times that of the Sun and is also almost 100,000 times more luminous. If it were located at the center of our solar system it would extend out between the orbits of Mars and Jupiter. Formed a mere 10 million years ago it is evolving rapidly and will most likely and its life in a supernova explosion some hundred thousand years from now.
Rigel is similar in age and mass but somewhat smaller with a diameter about the size of the orbit of Mercury. With a helium core it will continue to fuse heavier elements and eventually expand into a red giant before it suffers the same fate as Betelgeuse.
A close look at the sword extending downward from the left side of the belt reveals that the middle star is actually a nebula and the bottom star is a double. This can easily be seen with a pair of binoculars.
Follow the line of the belt down and to the left where you will see the brightest star in our sky, Sirius. Sirius is nearby at only 8.6 light years and is known as the Dog Star for its location in the constellation Canis Major, one of Orion’s two hunting dogs. Sirius has a white dwarf companion that orbits it every 50 years, but since it is 10,000 times fainter it cannot be seen with the naked eye. Above serious is Procyon, eighth brightest star in the sky, which is also orbited by a faint white dwarf.
Continue up to a pair of stars almost directly overhead. Castor and Pollux appear equally bright and are in the constellation Gemini, the Twins.
To the right of Gemini and directly above Orion is the constellation Auriga, the charioteer. Its brightest star. Capella, is very similar to our Sun, shining with a noticeably golden color. Complete the tour by continuing down to a V-shaped grouping of stars, the brightest of which is another red giant, Aldebaran. The group is actually a distant star cluster known as the Hyades. At 65 light years, Aldebaran is really much closer and represents the eye of Taurus, the bull.
Next month we’ll take a look at the constellation LEO, another gem up in the sky.
This month in history:
• March 1: Venera 3 impacts on Venus – 1966
• March 4: Jupiter’s ring is discovered – 1979
• March 14: Albert Einstein born – 1879; Gene Cernan born – 1934
• March 18: Voskhod 2 cosmonaut, Alexei Leonov, makes worlds first spacewalk – 1965
• March 22: Comet Hale-Bopp passes closest to Earth – 1997
• March 31: Saturn’s largest moon, Titan, discovered by Dutch astronomer Christiaan Huygens – 1655
