Skywatch Line for Monday and Tuesday, March 5th and 6th, 2018

This is the Skywatch Line for Monday and Tuesday, March 5th and 6th.

The Sun sets at 5:49 PM; night falls at 7:23. Dawn begins at 4:49 AM and ends with the Sun rising at 6:23.

The brightest evening planets are also the most difficult. Constellation Pisces hosts both. Venus, blazing at minus 4th magnitude, hovers about 6 degrees above the western horizon during Civil Dusk. Venus appears about 97 percent lit and 10.1 arc-seconds in size. Mercury, about 1 ½ degrees below Venus, is noticeably dimmer and smaller in our instruments and is 82 percent illuminated. Both lie within a binocular field for three weeks. Note their positions, both climb higher in the evening sky. However, Venus will entertain us until Autumn, while Mercury races higher until it reaches its greatest separation from the Sun on March 15th, and drops back. This is Mercury’s best evening apparition this year. Binoculars are recommended to see these inner planets amid the setting Sun’s glare. Venus sets at 6:55 PM, Mercury at 7:01.

Pisces also contains Uranus. It appears about 6th magnitude and is a tiny 3.4 arc-seconds in our instruments. By nightfall, is about 20 degrees high in the southwestern sky and about 2 degrees from the star Omicron Piscium. Uranus sets at 9:17 PM.

Dwarf Planet 1Ceres inhabits Cancer. The 7th magnitude former asteroid appears as a tiny 0.7 arc-second dot. At Midnight, Ceres is about 62 degrees high, and about 3 degrees from the star Iota Cancri. Detailed star charts are required to locate it. It sets at 6:16 AM.

The constellation Libra contains the Moon and Jupiter on Monday night. The 19-day-old Moon rose at 10:01 PM, blazes at minus 11th magnitude and appears about 80 percent lit. Tuesday, the Moon remains in Libra, slightly dimmer and smaller; it rises at 11:04 PM.

Jupiter rises shortly after Monday’s Moon at 11:25 PM. It lies about 14 degrees below the Moon Monday night, and around 4 degrees the next night. By Midnight on Tuesday, Jupiter is high enough for telescopic observers. The Great Red Spot (a giant storm on Jupiter) is visible at 3:42 AM. Also, that night, the Moon IO disappears behind the planet at 2:03 AM and reappears at 5:21 AM. Wednesday, at 12:11 AM, IO begins to cross Jupiter’s face and ends its trek at 2:39 AM. IO’s shadow exits the planet 1:32 AM.

Mars rises in Ophiuchus at 2 AM, appears about 89 percent illuminated and 5.9 arc-seconds in size. Mars appears to chase Saturn this month; notice the shrinking distance between them.

Saturn remains in Sagittarius, rising at 2:58 AM. Like Mars, it brightens a bit an also grows slightly larger.

Most constellations depict to mythical people or objects. In the 16th and 17th centuries, new constellations celebrated recently discovered star patterns and high technology of the times. One of these constellations is Sextans, the Sextant. Sextans is found between Leo’s front paws and the constellation Hydra.

Johannes Hevelius was a Polish astronomer in the port city of Gdansk (also known as Danzig). Prominent in local politics, his true passion was astronomy. In 1641, he built a private observatory that included a 150-foot telescope.
He was inducted into Britain’s Royal Society in 1664. However, he did most of his work with a six-foot brass sextant. A sextant contains an arc, one-sixth of a circle. It has a moveable arm that permits measurement of angles. In 1679, fire destroyed his observatory. He immortalized his loss with an invented constellation, Sextans, and rebuilt his observatory. Sextants still exist. Sailors use a version which includes a small telescope on the swinging arm and mirrors. Along with an accurate clock and astronomical almanac, the navigator locates his position at sea. That skill is being lost to the increasing use of GPS to fix a position with unprecedented accuracy.

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