What Is That Very Bright Star?
By: Irene & Steve Little
It is not a star, it is the planet Venus. Seen in the southwest shortly after sunset, Venus becomes easily visible in twilight and it is by far the brightest starlike object in the sky. If you know where to look, you can even see Venus in the sky before the sun sets (!) it is so bright. Every time Venus becomes this bright evening star, we get calls wanting to know what it is and why.
Venus shines by sunlight reflecting from its brilliant white clouds. Since its orbit is smaller than the orbit of Earth, we see at times the sunlit side, part of the sunlit side or only its dark side as Venus comes between us and the sun. In other words, Venus goes through phases for the same reason that the moon goes through phases from new Venus to crescent to gibbous to full Venus as we see different portions of its sunlit surface. At full phase, Venus is on the far side of the sun from Earth, quite small and difficult to see past the sun. Only when Venus is relatively close to Earth will Venus be quite large and we can see a bright crescent either as an evening star as right now or as a very bright morning star in a couple of months.
The other planet visible right now is Saturn below the constellation of Leo, the Lion. Leo rises around 8 p.m. Saturn is fainter than usual because the rings of Saturn are almost edge-on to Earth and reflect much less light than usual. In September when the rings are completely edge-on to us, the rings will become invisible because they are so thin. That is like trying to see a sheet of paper edge-on from a distance.
We find winter to be a great time to look for constellations. Orion, the mighty hunter, is quite high in the southern sky in the early evening. After the Big Dipper, Orion is the most easily recognized constellation because it has many bright stars in it. Orion’s belt of three equally bright stars is easily recognized. Orion’s shoulders above the belt consist of the red supergiant Betelgeuse on the left and white Bellatrix on the right. The right foot, blue Rigel, is very bright. Below the belt lie three much fainter stars in a line pointing down. These stars are called the sword. The middle star of this trio is the star-forming region M42, the Orion nebula. Even in a small telescope or even binocular, you can see the fuzzy gas-cloud extending into space.
Orion is a wonderful constellation to use as a guide to find other constellations. Following the three belt stars to the left, leads you to the brightest star in the sky, Sirius, the dog star. Sirius is the brightest star in the constellation of Canis Major, the big dog. Canis Minor, the small dog, and Canis Major are the hunting dogs of Orion. To find Procyon, the one bright star in the constellation of Canis Minor make an equilateral triangle with Betelgeuse, the left shoulder of Orion and Sirius. Going back to the belt stars, follow them to the right. That will get you into the constellation of Taurus, the bull.
The red eye of Taurus is made by the bright red star Aldebaran. On the left shoulder of Taurus you will find the small group of stars called the Pleiades, the seven sisters. Only 6 of the Pleiades stars are easily seen unless you have very good eyesight. We always say that the seventh sister is shy and is hiding. According to Greek mythology, Orion was attacked by Taurus as he was hunting a rabbit with his hunting dogs. The rabbit Lepus is a trapezoid of stars and can be found directly below the feet of Orion. To find Gemini, the twins, look from Rigel (right foot), past Betelgeuse (left shoulder) across the Milky Way to two bright stars. These are the heads of the twins Pollux and Castor. The bodies of the twins are irregular lines of stars pointing to the Milky Way. If you have read the Iliad, the names of the twins will be very familiar to you.
Good hunting in the winter sky.