This is the Dudley Observatory Skywatch Line for Wednesday, October 14th, and Thursday, October 15th, written by Louis Suarato.
The 5% illuminated, waning crescent Moon sets at 5:36 p.m. Wednesday. Look for the Moon as a 3% illuminated crescent Thursday in the pre-dawn sky below Venus. For the next two weeks, look for the zodiacal light in the east before sunrise. The zodiacal light is comprised of interplanetary dust particles illuminated by the Sun. this conical shaped light can be seen through the end of the month. Mars, one day past its opposition, glows at magnitude -2.61, above the eastern horizon after sunset. Mars remains in the sky the entire night. While Mars is rising in the east, Saturn and Jupiter will be high over the southern horizon, 6.5 degree apart. The two gas giants will set before midnight.
Take advantage of these moonless nights to get a good view of M31, the Andromeda Galaxy. Our closest large neighboring galaxy will be about 50 degrees above the east-northeastern horizon after 8 pm. Use Cassiopeia’s deeper V to point the way 15 degrees to Andromeda. M31 is 2.5 million light-years from Earth, and 220,000 light-years wide. The Milky Way is estimated to be 105,000 light-years wide. The Andromeda Galaxy is estimated to contain over 1 trillion stars, compared to the Milky Way’s estimated 200 billion stars. Andromeda is categorized as a barred spiral galaxy. Its center is dissected by a central bar of bright stars. Look about 12 degrees below the Andromeda Galaxy for M33, the Pinwheel or Triangulum Galaxy. Along with the Milky Way and the Andromeda Galaxy, the Triangulum Galaxy is part of what is known as the Local Group. The Local Group is made up of 54 galaxies, most of them dwarf galaxies. The gravitational center is somewhere between Andromeda and the Milky Way. M33is also a barred spiral galaxy, and is about 60,000 light-years wide and contains approximately 40 billion stars. At 2.7 million light-years away, the Triangulum Galaxy is a bit farther away than the Andromeda Galaxy. The Triangulum Galaxy is speeding toward the Milky Way at 180 miles per second. Data obtained from the European Space Agency’s Gaia mission suggest that the Triangulum Galaxy is either on a billion year orbit around Andromeda, and may have fallen into it in the past, or is on its first in-fall.