This is the Skywatch Line for Monday and Tuesday, July 2nd and 3rd.
The Sun sets at 8:37 PM; night falls at 10:52. Dawn begins at 3:07 AM and ends with the Sun rising at 5:22.
The darkening sky holds several bright planets. Mercury, in Cancer, shines with zero magnitude and appears about 57% illuminated. The observer should view it first, since it lies only 8º above the western horizon and sets at 10:06 PM. Mercury replaces Venus as The Beehive’s neighbor; it lies about 2º west of the star cluster.
Venus, the brightest of the planets, blazes with minus 4th magnitude, appears 16 arc-seconds in size and is about 70% lit. It is found about 17º above the western horizon and is 8º west of Regulus, Leo’s brightest star. It sets at 10:55 PM.
Jupiter is second brightest, inhabiting Libra and glowing with minus 2nd magnitude. The giant planet still clings close to Zubenelgenubi, the constellation’s brightest star. It is highest about 8:56 PM. Telescope users can see the Great Red Spot (a giant storm) at 9:48 PM, Monday. They can also see the Jovian moon Ganymede finish its crossing at 10:21 PM, followed by its shadow beginning its own trip of Jupiter’s face at 12:58 AM on Tuesday.
Saturn, in Sagittarius, rose before sunset and, by nightfall, shines with zero magnitude and lies about 10º above the eastern horizon. While easily visible in binoculars, its glorious ring system is best appreciated in a telescope at 12:34 AM. Asteroid 4Vesta, in Ophiuchus, is still relatively bright with fifth magnitude and lies about 9º west of Saturn and 5 ½º west of the star cluster M20. Best observed at 11:53 PM, it can be located with the assist of detailed sky charts available from astronomical media. Vesta sets at 4:33 AM.
Mars inhabits Capricornus. It rises about 10:31 PM, shines with minus 2nd magnitude and, through telescopes, appears about 97% lit. At Midnight, it is only 12º high above the eastern horizon. It is best observed at 3:01 AM. However, NASA reports that the global dust storm has not yet abated.
Mars rover Opportunity shut itself down, due to its solar panels being covered by Martian dirt. Rover Curiosity is still operating, due to its nuclear power. Its pictures and reports still show degraded views.
Neptune shares Aquarius with the Moon. Rising at 11:42 PM, it lies about 11º east of the blazing Moon. Seeing the 8th magnitude blue-green planet may be difficult. The waning, minus 11th magnitude Moon rises at 11:28 PM on Monday and at 11:56 PM on Tuesday. The Moon appears about 78% lit on Tuesday Dawn, and 69% lit on Wednesday. Wednesday’s Dawn sees the Moon just below Neptune, making observation of the planet even more difficult.
Wednesday, the Fourth of July is famous for fireworks. In the year 1054, Nature staged her own fireworks show. Chinese astronomers saw a new object in Taurus. Eyewitness accounts said it “shone like a comet.” This “guest star” shone in daylight for 23 days and was visible nightly for a year and a half. Many textbooks remark that no one in Europe or the Mid-East saw it. However, North American Natives saw it and made rock carvings depicting it. Charles Messier made it the first in his list of false comet objects. We now know the supernova blast blazed with the brightness of 500 million suns and produced a pulsar, a residue body that spins rapidly and emits regular radio pulses.