This is the Skywatch Line for Monday and Tuesday, May 6th and 7th.
The Sun sets at 8:01 PM; night falls at 9:55. Dawn begins at 3:48 AM and ends with sunrise at 5:42.
In Taurus, Mars remains as the sole planet in the evening sky. The Red Planet is ending its appearance in our Spring sky. It appears about 96% illuminated, glows with first magnitude and is only 4 arc-seconds in size. By Civil Dusk, it is about 27º high in the southwestern sky and sets at 11:14 PM. Monday night finds it between the Bull’s horns, about 2º above the red star Aldebaran; Tuesday shows it about 3º above the Moon, with the Crab Nebula sandwiched between them.
The Moon shares Taurus with Mars on both nights. Monday, it appears as a 5% crescent, 2-day-old Moon, blazing with minus 3rd magnitude and about 13º high in the West. Tuesday finds it brighter and wider. As mentioned above, it lies close to Mars, appearing about 24º high. It sets at 9:57 PM on Monday, and at 11:02 on Tuesday.
Midnight displays a temporary visitor to our skies; the Dwarf Planet Ceres (formally classified as an asteroid) inhabits Ophiuchus. Ceres was the first asteroid discovered. It was detected on Jan 1, 1801. Ceres was the Roman goddess of agriculture and taught humans to grow grain. Ceres orbits the Sun about midway between Jupiter and Mars. It is the largest main belt asteroid, about 585 miles (940km) diameter. It is about 25% ice and even has a thin haze of water vapor for an atmosphere, discovered by the Dawn spacecraft in March 2015. Ceres will continue to shine with at least 7th magnitude from now to June 19th. It lies about 9º above Jupiter; finder charts are available from several online websites. It rises at 9:50 PM and is best observed at 2:48 AM.
As mentioned, Jupiter shares Ophiuchus with Ceres. It rises at 10:54 PM, shining with minus 2nd magnitude, appears about 44 arc-seconds in size and is about 25º high at Midnight. It is best observed at 3:26 AM. At that time, Tuesday, the Great Red Spot is telescopically visible. That same night, the Jovian Moon Ganymede begins to cross the planet’s face at 3:42 AM.
Saturn is visible for about half the night. In Sagittarius, the Ringed Planet rises at 12:46 AM, shines with zero magnitude and appears about 1/3 Jupiter’s size. It is highest at 5:24 AM, during Civil Dawn.
Neptune rises in Aquarius at 3:31 AM. The 8th magnitude planet is only 2 arc-seconds in size, posing challenges to the observer because of the brightening Dawn sky.
Venus rises in Pisces at 4:46 AM, appearing about 90% lit, blazing with minus 4th magnitude and 11 arc-seconds in size. It, too, has to contend with the brightening dawn sky. But, binoculars or telescope should permit viewing the planet, which is soon to disappear behind the solar glare.
There is a lot of confusion about asteroids. The “asteroid belt” is usually pictured in movies as an almost solid disk of huge rocks. Actually, there are many thousands of miles between rocks of varying sizes. Scientists think they know the composition of some asteroids, from meteorites. Several spacecraft are on the way to study asteroids, and others are in various stages of planning.