February 2015 - Vol. 19, 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 is 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 hat passes through Cassiopeia. It will not be visible in bright Moon light or in the cities.

MERCURY appears in the early morning sky in the second week of February. VENUS rises from the western horizon in the evening sky, look for a conjunction with Mars and the moon around the 20th.. JUPITER will be at opposition on February 6, watch the giant planet as it approaches the Beehive cluster. MARS moves from Aquarius to Pisces, setting in the early evening. The red planet will be within .5 deg. of Venus on February 22. SATURN rises higher in the morning sky. URANUS sets in the evening, look in the constellation of Pisces.

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	Venus .8 deg S of Neptune.
04	Jupiter 5 deg N. of Moon.
06	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 meteoroids 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. May be seen for the next two weeks.
06	Jupiter at opposition. Moon at apogee.
13	Saturn 2 deg S. of Moon.
14	Mars and Venus less than 4 deg apart.
17	Mercury 3 deg S. of the Moon.
19	Moon at perigee, expect high tides.
21	Venus .5 deg S. of Mars, 2 deg S. of the Moon. Mars 1.5 deg S. of Moon. Uranus .6 deg S. of Moon, occultation from U.S., Mexico.
24	Mercury greatest elongation W.
25	Aldebaran 1 deg S of Moon, this will be an occultation from Alaska, Canada, Greenland, Iceland, Scandinavia and parts of northern Russia.
26	Neptune in conjunction with the Sun..

Lunar Almanac for February 2015

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 18	Deep Space Objects
	1st. Qtr 25	Planets & Moon
	Full 3	Moon
	Last Qtr 12	Deep Space & Planets

Sirius, the Dog Star

The distinction of "brightest star in the night sky" goes to the blue giant star, Sirius, Alpha Canis Majoris, also known as the "Dog Star". Sirius shines so brightly in the night sky because of its luminosity, that is 25 times the luminosity of our own Sun, and because it is relatively close to Earth, a mere 8.6 light years distant. The name Sirius comes from the Greek and means the Sparkling One or the Scorching One, so called because of the fact it rises with the Sun (heliacal rising) during the hottest month of the year (August) giving rise to the expressing "dog days" of Summer.

Sirius was used in ancient Egypt to predict the rising of the Nile waters. In Egypt, it was known as Sothis, or the star of Isis. Called the Nile Star, Sirius appeared in the morning sky just before the flood waters rose. The star is 1.8 times the diameter and 2.35 more massive. It is a white star with a spectral type of A1V.

Sirius may be part of a cluster of stars known as the Ursa Major star stream. Stars in the Ursa Major stream appear to be moving in a different direction than our own Sun which helps to account for the large proper motion of the stars of this cluster. In recent years, the membership of Sirius in this star stream has been questioned.

Sirius has been noted by astronomers all over the world from the beginning of recorded history. It has been noted as the brightest star in the night sky. It has been identified repeatedly as part of a constellation of a dog, perhaps because of its proximity to the great hunter constellation of Orion. In China, the constellation was referred to as the Heavenly Wolf. Sirius is part of the so-called Winter triangle formed by the first magnitude stars, Procyon and Betelgeuse.

In 1844, Friedrich Bessel, observed that the proper motion of Sirius indicated that it had a companion star. The companion star is a white dwarf, that has been dubbed, "The Pup", that was discovered by telescope maker, Alvin Clark while testing a new 18.5-inch refractor in 1862. It was the largest refractor at the time of the sighting, that was confirmed later that year in other telescopes. The visual component of the binary system is referred to as Sirius A and the companion is called Sirius B. A third component of the system is suspected, but it is too faint to observe in the glare of the brighter members.

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

This installment of "Whats Up?" is ©2014 by Dawn Jenkins for Astra's Stargate. View Ron Leeseburg's Farewell Issue for information on where to find information such as is presented in this almanac.