Skywatch week of June 3rd, 2019

Tue Jun 4, 2019 NAME THAT PLANET Let’s play a game I call, “name that planet.” I’ll give you the names of some or all of the moons that orbit a particular planet, and you have to figure out which planet it is. For example, if I said, “luna” or “moon,” you would respond with “earth.” All right, let’s start. “Phobos” and “Deimos,” which mean “fear” and “panic?” These are the two sons, and also, the two moons, of Mars. Now try “Nix,” “Styx,” “Hydra,” “Kerberos,” and “Charon.” These are the five moons of Pluto. How about, “Juliet,” “Ariel,” “Umbriel,” “Titania,” “Puck,” and “Miranda?” Those are some of the moons of Uranus. “Adrastea,” “Metis,” “Amalthea,” “Callisto,” “Ganymede,” “Europa,” and “Io?” Those belong to Jupiter. Now try, “Rhea,” “Mimas,” “Enceladus,” “Atlas,” “Calypso,” “Dione,” “Epimetheus,” “Pandora,” “Prometheus,” “Janus,” and “Titan?” Those moons orbit Saturn. That leaves us with just Mercury and Venus, but they don’t have any moons!

Wed Jun 5, 2019 JOHN COUCH ADAMS John Couch Adams was born 200 years ago today, on June 5th in 1819. Adams was first to predict the location of Neptune. Astronomers had noticed that Uranus, thought at the time to be the outermost planet, did not follow its predicted path. The gravity of some massive object farther out was pulling on it, altering its orbit. In 1845, Adams deduced the location of the hidden gravity source, and in 1846, Neptune was discovered telescopically by J.G. Galle; but Galle had never heard of Adams! Galle used the predictions of the French mathematician Jean Leverrier instead, who had also arrived at a solution to the orbit problem a year after Adams. But Adams had sent his calculations to his supervisor, the Astronomer Royal, George Airy, who didn’t do anything with the information because Adams hadn’t shown all his work and didn’t follow through with Airy’s request for more information and never made an appointment to talk to him about it – definitely a failure to communicate.

Thu Jun 6, 2019 NAME THAT CONSTELLATION – JUNE Can you identify the thirty-first largest constellation in the sky? It is bordered on the north by the constellation Lynx the Bobcat, and on the south by Hydra the Water Snake, on the west by Gemini the Twins, and on the east by Leo the Lion. There are no bright stars in this constellation, and it is one of the darkest regions in the night sky. But there is a beautiful open star cluster within its borders known as the Praesepe or Beehive cluster, and some of its stars have been found to have planets orbiting them. In mythology this animal represents a crustacean that was sent by the goddess Hera to attack the hero Hercules. It was accidentally crushed by Hercules during the fight, but Hera restored it to life in the heavens as a constellation. Tonight the waxing crescent moon is nestled among its stars. Can you name this star figure, the third constellation of the Zodiac? The answer is Cancer the Crab, in the southwest after sunset.

Fri Jun 7, 2019 GIOVANNI CASSINI Giovanni Cassini, one of the seventeenth century’s most distinguished astronomers, was born on June 8th, 1625. In 1665, Cassini made the first detailed observations of Jupiter’s Great Red Spot, an immense 400 mile-an-hour storm a couple of times larger than earth. In 1675, he discovered a gap about two-thirds of the way out in Saturn’s ring system, something we now call the Cassini Division. Saturn’s rings are made up of billions of tiny moonlets of water ice, ranging in size from icebergs down to fist-sized and smaller particles. The gap that Cassini discovered is something of an illusion - there are ice chunks there, just not quite as plentiful as elsewhere. Both Jupiter and Saturn are visible in our evening sky: Jupiter, in the constellation Scorpius, rises an hour after sunset, and shines very bright in the southeast sky; Saturn doesn’t appear until near midnight, in Sagittarius, in the southeast after sunset.