This is the Dudley Observatory Skywatch Line for Wednesday, July 6th and Thursday, July 7th written by Louis Suarato
The 8% illuminated, 2 day, 9 hour old, waxing crescent Moon sets at 10:04 p.m. Wednesday. Look for Jupiter to the Moon’s upper left, about 25 degrees over the west-southwestern horizon. Regulus, the constellation Leo’s brightest star, can be seen between the Moon and Jupiter. Regulus will be about 3 degrees north of the crescent Moon, Thursday night. If your telescope is large enough, you’ll be able to see Jupiter’s moon Io, begin its transit at 10:16 p.m. Thursday. Jupiter has a new visitor as NASA’s unmanned spacecraft, Juno, is at the beginning of its mission to analyze the planet’s atmosphere, including its composition, temperature, cloud motions, and other properties. Scientists believe the data derived from Juno will provide information about Jupiter’s development and evolution, and lead to knowledge of the solar system’s formation. Juno will orbit Jupiter for the next 20 months, making 37 orbits around the solar system’s largest planet.
By 10:30 p.m., the entire constellation of Scorpius will be above the southern horizon, with Saturn and Mars on either side of its claws. If your skies are dark, and horizons are clear enough, you can see the Milky Way rise up from the northern horizon through the Double Cluster and Cassiopeia, and up through Cygnus the Swan over the eastern horizon. The Milky Way turns down toward the constellation Aquila, and its brightest star, Altair. The view of our galaxy ends at the southern horizon after forming the steam from the Teapot asterism in Sagittarius.
July 7th is the birthdate of Swiss astronomer Rudolf Wolf. Born 200 years ago, Wolf is known for his research of sunspots. Wolf’s interest in sunspots began in December 1847, while observing an especially large and spectacular group. Wolf continued his solar observations for the next 46 years. In addition, Wolf collected sunspot data going back to 1610. Using this data, Wolf concluded there was a coincidence between the 11 year sunspot cycle and the cycle of geomagnetic activity. The sunspot number, as we know it today, is devised using a formula developed by Wolf in 1848.