This is the Skywatch Line for Monday and Tuesday, February 11th and 12th.
The Sun sets at 5:21 PM; night falls at 6:57. Dawn begins at 5:21 AM and ends with the Sun rising at 6:57.
The 6-day-old Moon dominates the night sky. Monday’s Moon occupies Cetus, appearing about 40% illuminated, about 31 arc-minutes in size and blazes with 9th magnitude. It sets shortly after Midnight. Tuesday’s First Quarter Moon occupies Taurus, is about 50% lit and slightly brighter; it sets shortly after 1 AM.
Mercury makes a brief reappearance in our sky. In Aquarius, it appears about 94% lit, shimmers with minus 1st magnitude, presents a 5.2 arc-second size and lies about 7º above the western horizon. An unobstructed horizon and binoculars are helpful in finding this famously elusive planet. It sets at 6:08 PM.
Neptune, also in Aquarius, glows with 8th magnitude about 12º above Mercury, appears 2 arc-seconds in size and is about 19º above the horizon. It sets at 7:14 PM.
Mars is still the most easily seen planet in the evening sky. In Pisces, it shines with 1st magnitude, appears about 6 arc-seconds in size and is about 90% lit. It sets at 10:58 PM. Uranus, 1 degree next to Mars, forms a nice conjunction with the Red Planet, and that makes it easier to see in the same binocular or finder scope field. In Aries, Uranus shines with 5th magnitude, but is a small 3 arc-seconds in size. Both Mars and Uranus lie about 55º high in the South. However, the brilliant Moon, about 14º away, may hinder seeing Uranus on Monday night. Tuesday evening, the Moon is further away and may make observing this distant planet easier. Uranus sets at 11:00 PM.
Comet 46P/Wirtanen is still inhabits Ursa Major. The comet is near star Theta at 9 PM. Observers continue to report it at about 8th magnitude. Even though it is in far Cetus or Taurus, the Moon may wash out the thin cometary coma and tail. Again, binoculars may help.
Another comet, Iwamoto, is becoming prominent in our skies. Closest to the Sun on February 6th, it races from Virgo to Cancer in a week. On the night of February 10/11, it will be about 1º from a trio of galaxies (M 95, 96, 105) beneath the Lion’s belly. On the night of the 13th, it lies about 3 arc-minutes from NGC 2903, a galaxy at the tip of Leo’s nose. Reports indicate a magnitude between 6th and 7th, within the ability of binoculars and small telescopes.
Dawn brings new players on stage. Jupiter still occupies Ophiuchus, shining with minus 2nd magnitude and a large 35 arc-seconds in size. Rising at 3:08 AM, it lies about 17º high in the East at Dawn.
Venus and Saturn share Sagittarius. Venus rises at 4:29 AM, appearing about 66% lit, blazes with minus 4th magnitude, and appears about 7º high at Dawn. Saturn shines with zero magnitude is about 15 arc-seconds in size and is about 3º high at Dawn, but is 12º altitude at Civil Dawn. Saturn rises at 5:01 AM. Notice the distance between Venus and Saturn. Venus is gradually becoming lower daily. At Civil Dawn, they are separated by about 6º. About a week from now, they will be about 1º from each other.
Polaris, the Pole or North Star, is one of the most famous of all stars. Many people think that it is the brightest; it is not, only second magnitude. Its importance is an accident of place; Polaris happens to occupy the spot closest to true North. In a few thousand years, it will drift away, and another star will become the Pole Star. Many do not know that it is a multiple star system. Using the Hubble Telescope, astronomers recently discovered a third member. By analyzing the stars’ orbits, they “weighed” Polaris, and found it about four times heavier than our own Sun. Polaris has one distinction. Not many people know that it is a variable star; it periodically brightens and dims. Polaris is a Cepheid variable; in fact, it is the brightest of its kind in our sky. Cepheids are valuable stars. The period of their variation is in direct ratio to their brightness. So, if an observer sees a Cepheid and tracks its cycles, he can determine its intrinsic brilliance and also derive its distance from us.