What's Up in the Night Sky

March 2015 - Vol. 19, No. 3

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.

Look S as night falls to see the brightest star of the evening, SIRIUS (Canis Major). Look to its upper right to find the familiar "hour glass" asterism of constellation Orion with bright white RIGEL (lower right) and red BETELGEUSE (upper left). Below the three Belt stars, lies the Great Orion Nebula (M42 & M43) visible to the naked eye as a hazy patch of light. Now shift your gaze to the left to find another bright star, PROCYON (Canis Minor) the upper star of the "Winter Triangle" mentioned last month. Above Procyon, and to its left, Saturn glows brightly and above Saturn at to its right are the Gemini twins, POLLUX and CASTOR. As the month progresses and winter becomes spring, orange ALDEBARAN (Taurus) comes into view to the W. Just to the left of Aldebaran, a star cluster, the HYADES, might be faintly visible under dark sky conditions. Above that glows the more famous cluster, the PLEIADES (M45). Although smaller that the Hyades, it is much brighter and should be visible as another hazy patch of light. Some may even be able to make out the tiny "dipper" arrangement of its eight brightest stars. High above and a bit to the right is brilliant CAPELLA (Auriga) and farther right is the famous "W" asterism of Cassiopeia.

MERCURY reaches aphelion on March 6, this apparition favors southern observers. VENUS appears in the evening sky. JUPITER just past opposition is still visible most of the night. MARS is low in the west at sunset. SATURN rises around midnight. URANUS disappears in the west at mid-month. This month's Total Solar Eclipse will be best seen from the northern Atlantic, but the partial eclipse will be visible in north Africa, Europe and western Asia. The eclipse occurs on the same day as the Earth is at Equinox. The Moon will actual be quite near to perigee, which normally results in a long eclipse, but this northern eclipse will only be 2:46 minutes in duration at the eclipse center. This does, however, produce a wide path of totality.

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
03	Jupiter 5 deg N. of Moon.
04	Venus .1 deg N of Uranus.
05	Moon at apogee.
08	Daylight Savings Time begins. 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.
11	Mars .3 deg N of Uranus.
12	Saturn 2 deg S. of Moon.
14	Saturn stationary in Scorpius.
17	Mercury 1.6 deg S of Neptune.
19	Mercury 5 deg S. of the Moon. Moon at perigee, expect high tides.
20	Total Solar eclipse. The best places to observe from are the Faroe Islands and Svalbard. Equinox, night and day are equal and the Sun appears due East at sunrise and due West at sunset.
21	Mars 1.5 deg S. of Moon,occultation from parts of western Antarctica, southwestern South America. Uranus .1 deg S. of Moon, occultation from Brazil, central and western Africa, Middle East. Mars 1 deg N. of the Moon.
22	Venus 3 deg N. of Moon.
25	Aldebaran .9 deg S. of Moon, this will be an occultation from northern Russia, Alaska, northwestern Canada, northern Greenland, Scandinavia, and parts of northern China.
30	Jupiter 6 deg N. of Moon.

Lunar Almanac for March 2015

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 20	Deep Space Objects
	1st. Qtr 27	Planets & Moon
	Full 5	Moon
	Last Qtr 13	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 in Canis Major

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