What's Up in the Night Sky

March 2017 - Vol. 21, 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.

The constellations Taurus, with its Pleiades (a tiny "dipper-like" asterism), Orion and the Winter Triangle are now sinking in the W. Castor and Pollux (the Gemini "twins") are shining in the NW while Capella (Auriga) glows above them. Regulus (Leo) shines high in the S as the wandering constellation Hydra appears to create a void below since it has no bright stars. The "Big Dipper" asterism (Ursa Major) high in the NE has appeared to "rotate" so its "handle" is now nearly horizontal. Spica (Virgo) and Arcturus (Bootes) are now rising in the E. Spring is coming to the north! .

MERCURY emerges in the evening sky after superior conjunction on the 7th. The fleet-footed planet appears in the evening sky, best observed from the middle north en latitudes. VENUS having provided a shining evening apparition, passes 8 deg N of the Sun at inferior conjunction on the 25th. Our sister planet could possibly be observed in the evening and the morning twilight for those who may wish to attempt it. The planet will emerge in the Morning sky by month's end. MARS moves into Aries on the 8th, will appear close to the moon on the first day of the month. JUPITER in retrograde motion will remain in Virgo until opposition on April 8. SATURN still low in the early morning sky. URANUS vanishes from the evening sky by month's end. The outer planet NEPTUNE will not be visible this month.

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 or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
01	Mars 4 deg N. of Moon
02	Neptune conjunction with the Sun. Ceres .8 deg S. of the Moon, occultation observable from south South America, Antarctic Peninsula, and South Georgia. The minor planet is 7.4 magnitude so optical aid will be required to observe this event. Binoculars may serve unless accurate timings are desired.
03	Moon at perigee.
05	Aldebaran 0.2 deg S. of the Moon occultation from Soloman Islands, Micronesia, Hawaii, North and Central America, and western Caribbean.
10	Regulus .8 deg N. of Moon, occultation from Southeast South American, South Georgia, Queen Maud Land, and South tip of Africa.
12	Daylight Savings Time begins. In affected areas, clocks spring ahead 1 hour.
14	Jupiter 2 deg S. 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 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. This effect may be visible for the next two weeks on dark, clear nights.
18	Moon at apogee.
20	Equinox, Spring arrives in the northern hemisphere, fall opens in the southern hemisphere. Saturn 3 deg. S. of Moon.
25	Venus at Inferior Conjunction.
26	Neptune .005 deg of Moon, occultation from Ascension Island, South Africa, north Madagascar, Yemen, Oman, and Southwest Asia
27	Mercury 2 deg. N. of Uranus
30	Moon at perigee.

Lunar Almanac for March 2017

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 28	Deep Space Objects
	1st. Qtr 05	Planets & Moon
	Full 12	Moon
	Last Qtr 20	Deep Space & Planets

Topic of the month: Cancer the Crab

The constellation of Cancer (the crab) finder chart

The constellation of Cancer is associated with a crab. None of the stars in this constellation are brighter than 3.7 magnitude, making it hard to observe under city lights. It is located squarely on the ecliptic and it is also the faintest ecliptic constellation. About 2000 years ago it was quite important to astronomers because it was the constellation where the Sun was located at Summer Solstice, For this reason, the constellation lent its name to the Tropic of Cancer, one of the five major circles of latitude on the planet. This is the northernmost location that the Sun can pass overhead at noon, about 23 degrees above the equator.

The alpha star of this constellation is also named Acubens or "claw." Beta Cancri, known as Al Tarf is the brightest star in this constellation. Delta Cancri, called Asellus Australis is a yellow giant star shining at mag 3.9. It is the second brightest star of the Crab constellation. Perhaps the most interesting star of the constellation is Tegmen, or Zeta Cancri a fine multiple star system. The system is composed of two binary stars, Zeta-1 Cancri and Zeta-2 Cancri. Zeta -1 is a pair of yellow dwarf stars. Zeta -2 contains two yellow type G stars and a 10th magnitude red dwarf star. The system’s its proximity to the ecliptic means that it can be occulted by the moon and (rarely) by planets.

The brightest jewel of this constellation is the open star cluster M-44, commonly called the Beehive cluster or Praesepe. Praesepe comes from Latin where it originally meant manger or alternately, hive. So whether you call it a beehive, a manger, M-44, or NGC 2632 most observers will know what object you are referring to: a bright cluster of about 40 members located in the constellation of Cancer. Recent studies have identified about 870 stars as proper members of this cluster but a backyard observer will never identify this many stars in the Beehive cluster. A naked eye observer will see a misty patch of stars in the center of the constellation, with the star Epsilon Cancri of the constellation being a member (mag ~8). The distance to this cluster is not exactly known, but 580 light years is a typical value that is given. This may be because of the great number of stars that are actual members of the cluster.

Another popular cluster, M-67 is also located in the constellation of Cancer. This galactic cluster is considered to have 500 or more members with about 100 visible in a large amateur telescope. The age of the cluster has been measured at about 4 billion years, it is the oldest open star cluster in the Messier catalog. In 2014, three extra-solar planets were discovered in the cluster using the 3.6m telescope at the La Silla Observatory in Chile.

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

The star chart above was generated by Stellarium, a free open source planetarium program. The above image was created by Dawn Jenkins, using Stellarium and a graphic editing program to format the image for this web page. Editing was done for educational purposes only. Stellarium offers much more to amateur astronomers and is being used in planetariums and to guide telescopes in the field. Simple charts like the one above can be used on the internet for non-profit, illustration purposes. Proper credit is due of course! Thank you to the makers of this fine program from Astra's Star Gate.