As we approach the summer solstice on June 21, you’ll notice that the Sun is almost at its highest at noon. Thanks to daylight saving time you’ll have to wait longer to see the stars. By nine o’clock you should be able to put on some bug spray, get away from street lights, and let your eyes become dark adapted, and enjoy the view.
It’s been a while since we looked at the Big Dipper. Let’s use it to find two constellations in the spring sky. Look in the north and find the dipper again. It should be high up with the bowl upside down and the handle bending toward the south. Now follow the bend of the big dipper down and to the south and you will come to the fourth brightest star in Earth’s sky, Arcturus. Astronomers use the mnemonic “Arc to Arcturus” to find it.
Due to the Earth’s rotation, Arcturus is always following the great bear, “Ursa Major” around the sky. The name Arcturus means the “bear watcher” in Arabic. Arcturus is 36 light years away, and is 170 time more luminous than our Sun. There are about 500 stars closer than Arcturus, but most of them are small “red dwarf” stars and too dim to see.
Arcturus is the brightest star in the constellation Boötes (boo-OH-teez), the herdsman. You can think of the herdsman guarding his flock from the bear. Don’t expect the constellation to look like a person though. To see a pattern, look instead for a kite figure with Arcturus as the bottom of the kite. (See the image)
Now let’s try to find another star pattern using the big dipper’s handle and Arcturus. This time arc to Arcturus and keep going down until your reach another bright star lower in the southern sky whose name is Spica. The mnemonic this time is “arc to Arcturus, then speed to Spica” Spica’s name signifies an ear of wheat held in the left hand of the goddess of the harvest. Spica is in the constellation is Virgo. It doesn’t look much like person either. A great help seeing Virgo is to download a sky map from https://skymaps.com/skymaps/tesmn2305.pdf Use the print out outside with a red flashlight so you won’t lose your night vision.
Virgo is an important constellation historically because it is one of the twelve zodiacal constellations. To be a zodiacal constellation means that the Sun appears to pass in front of that constellation at the same time every year. Virgo is in the sky behind the Sun in November, so it’s in the daytime sky behind the Sun. Ancient astronomers noticed that the Sun, Moon, and all the planets were only seen in the circle of zodiacal constellations. In the past, astronomers thought the movement and positions of the planets influenced the personality and behavior of people. We now know that this astrology is a pseudo-science, and it is completely baseless. We’ll talk about the zodiac more later. For now, enjoy finding Boötes and Virgo with Arcturus and Spica.
For questions or comments: James Hill, Mississippi NASA/JPL Solar System Ambassador. jhill6333@gmail.com
