Skywatch for the week of April 22, 2019
Tue Apr 23, 2019 NAME THAT MOON The moons of our solar system have many shared features, such as meteor impact craters, mountains, plains and valleys. See if you can identify the moon if I list some of those named features. This first moon has impact craters named Plato, Kepler, Copernicus, Galileo, Aristotle and Hevelius, plus great dark features like the Sea of Cold, the Bay of Rainbows, the Ocean of Storms and the Sea of Tranquility. This is easy, it’s the moon, our moon. What about El Dorado, Aztlan, Xanadu and Shangri-La? These features are found on Saturn’s largest moon, Titan. This next moon has lots of volcanoes with names like Thor and Loki, Marduk, Maui and Pele. The moon is Io and it orbits Jupiter. And finally, try Kirk, Spock, Uhura, the plains of Vulcan, Nemo, Skywalker, Ripley, Vader crater, the Tardis chasm, and a dark feature at its north pole named Mordor? These are found on Pluto’s largest moon, Charon.
Wed Apr 24, 2019 STAR NAMES AND DESIGNATIONS I like the sound of star names. Alpha Centauri, for instance, a mere 4 and a third light years away, is a favorite destination for many space travelers in science fiction. But it turns out that a lot of stars begin with “Alpha,” because that’s not actually the star’s name, but its designation. Rigel Kentaurus, which means, “the centaur’s knee,” is the actual name for Alpha Centauri. Alpha simply means it’s the brightest star in the constellation of the Centaur - so, Alpha Centauri. The star Arcturus, which you can see in the east this evening, is designated, Alpha Boötis, the brightest star of Boötes the Shepherd. To its south is Alpha Virginis, the brightest star in Virgo, named Spica. The second brightest star in a constellation is designated Beta, such as Merak, one of the stars in the Big Dipper. It’s designated Beta Ursa Majoris, because the Big Dipper is just a part of the constellation of Ursa Major, the Great Bear.
Thu Apr 25, 2019 EMPTY SPRING SKY Some parts of the sky have more bright stars than others. The stars are fairly randomly distributed, but it seems as though most of the really bright ones can be found in the winter evening sky. The evening skies of summer have some bright stars, too, but the fall sky and the spring sky are relatively empty of bright stars. There are a few exceptions - the stars Arcturus and Spica, in the east and the southeast this evening; and Regulus, which shines out from the heart of Leo the Lion, near the top of the sky. But this evening, most of the bright stars by far are actually holdovers from winter - brilliant Sirius and bright Procyon in the Greater and Lesser Dogs, Capella in Auriga the Charioteer, Castor and Pollux in Gemini, the Twins, plus Betelgeuse, Bellatrix, Rigel and Saiph, plus the belt stars, Alnitak, Alnilam and Mintaka of Orion the Hunter.
Fri Apr 26, 2019 ARCTURUS AND BOÖTES If you look off to the east tonight, or any night this month or next, you’ll find a star low in the sky after sunset. That eastern star is named Arcturus, which means, “bear chaser.” It’s called the bear chaser because Earth’s rotation causes this star to follow or “chase” the constellation of Ursa Major, the Great Bear in the Sky. The bear is to the north of Arcturus (you’ll recognize its back and tail as the Big Dipper, well up in the northeast.) Arcturus is in the constellation Boötes, the Herdsman. This is an agricultural constellation that farmers and shepherds used long ago to keep track of when to plant and harvest and tend to the sheep. In the springtime, Boötes is a celestial reminder for those who watch over their flocks at the time when lambs are born. And in the fall, Boötes is low in the western sky after sunset, a cosmic post-it note to farmers - bring in the crops.