What's Up in the Night Sky

February 2016 - Vol. 20, No. 2

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

A large asterism, the "Winter Triangle", appears directly overhead. It appears as an inverted triangle formed by three bright stars: Procyon (Canis Minor) upper left, Betelgeuse (Orion) upper right and Sirius (Canis Major) below center. The Big Dipper (Ursa Major's famous asterism) stands high in the NE with its "handle" still pointing towards the horizon. Follow the handle's curve to orange star Arcturus (Bootes). Look for Cassiopeia's "W" asterism high in the NW. To the S, Orion dominates the sky while Aldebaran (Taurus) followed by the Pleiades star cluster drops below the horizon by 3 AM. Regulus (Leo) now rises in the SE. If you live in a dark site region, don't forget to observe the Milky Way's (our spiral galaxy) arm that passes through Cassiopeia. It will not be visible in bright Moon light or in the cities.

MERCURY is visible in the morning sky this month and well placed for southern observers, reaches greatest elongation W on the 7th. VENUS shines in the morning sky, look for the queen of the sky near Mercury the second week of the month. MARS is still also in the morning sky, rising aound 1 am. JUPITER rules the night in Leo, approaching opposition in early March. SATURN also a morning object this month. The outer planet URANUS is in the evening sky, setting before midnight.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
02	Groundhog's Day is halfway between the solstice and equinox, also known as Candlemas Day. Astra predicts 6 more weeks of Winter in the northern hemisphere.
06	Venus 4 deg S. of Moon. Mercury 4 deg S. of Moon.
11	Moon at perigee.
13	Mercury 4 deg W. of Venus, not a true conjunction but it's fun to watch the dance of the planets.
20	Aldebaran 0.3 deg S. of the Moon occultation from Southeast Asia, southern China, Japan, Hawaii, western USA.
24	Jupiter 1.7 deg N. of Moon. Look W from a dark location, at about an hour after sunset, to view zodiacal light. ("Zodiacal light" is a vertical band of white light believed to be sunlight reflected from meteoriods found in the plane of the ecliptic, the apparent "path" of the Sun, Moon and Planets as they travel across our sky.) It will appear to be a very large, but very dim, pyramid of of white light, "leaning" to the left. This effect may be visible for the next two weeks on dark nights.
27	Moon at apogee.
28	Neptune conjunction with the Sun.
29	Leap Day, keeping our calendar synchronized!

Lunar Almanac for February 2016

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 08	Deep Space Objects
	1st. Qtr 15	Planets & Moon
	Full 22	Moon
	Last Qtr 01	Deep Space & Planets

Topic of the month: The Hyades

August 24, 2016 In the north, the evening winter sky sparkles, boasting of the brightest star as seen from Earth, the dog star Sirius and the giant hunter, Orion. They rule the sky with the bright stars and the twin constellation of Gemini. But they are are led across the night sky by the more northerly constellation of Taurus, the ecliptic constellation that has been associated with a bull. The bull is rather ignomatic to some, for although constellation maps may show horns, it is difficult to see more than one leg on the bull as it charges across the sky. The first magnitude star Aldebaran marks the eye of the bull, nestled in a triangular shaped group of stars that forms the "face" of the bull. The triangular face of the bull is a very important star cluster, the Hyades. The center of this cluster has been measured by astronomers to be located about 150 light years away from the Earth. The fiery eye of Aldebaran is not a member of the cluster, but resides about midway between our Sun and the Hyades center.

The Hyades cluster is nearby as clusters go, only the Ursa Major Star cluster is closer to us. The cluster was noted by ancient astronomers and was thought by some to indicate rain. It may be that when the cluster was prominent in the sky many locations on Earth experienced their "rainy" season. At least 10 stars in the cluster are fourth magnitude or brighter, with four of the brightest being well studied red giants. The brightest Hyades is the red giant Theta-2 Tauri, a spectroscopic binary. It forms a pair with Theta-1, a pleasure to observe with the naked eye, however the two stars are actually 4 light years apart and are not a true double star. The cluster is believed to be about 400 million years old based on star types of its members. The cluster may well appear best as a binocular object, contains no nebulousity and covers about 4.25 degrees of the sky.

The Hyades cluster is very important to astronomers because the proper motion of each individual star can be measured. Stars at the center of the cluster are moving at .11" annually, but outlying members show a more or less motion based on their position in the cluster. This means that the cluster itself is useful for establishing the size of the universe. The chart below shows the Henry Draper designations of the brightest members of the group except for the bright ones that have greek designations. The scale along the bottom is the right ascension and the verticle axis shows the declination. The bright star Aldebaran is the only non-member in this chart that has been labeled. This chart was originally created by Thuvan Dihn and licensed as stated below..

Details of the Hyades Cluster showing prominent members.

The Hyades will set around 2 am this month. They rise and set with the bright star Aldebaran and reside on the ecliptic opposite their famous half-sister, the Pleiades cluster. These two star clusters are among the finest in the night sky.

--See You Under the Stars!
Astra for Astra's Almanac

The star chart above was generated by Stellarium, a free open source planetarium program. This image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. The second image above was created by Thuvan Dihn and licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. It has been modified as allowed under the license by Dawn Jenkins and may be distributed as stated on the Wikimedia Commons website.