Events for February 2013

The following table gives the date and time of important astronomical events for February 2013. The time of each event is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). To convert GMT to Eastern Standard Time (EST) just subtract 5 hours. To convert GMT to other time zones, visit Time Zones. Some of the astronomical terms used in the calendar are explained in Definitions.

 Date    GMT   Astronomical Events for February 2013
------  -----  --------------------------------------------
        (h:m)
Feb 02  01:25  Spica 0.3°N of Moon
Feb 03  09:55  Saturn 3.5°N of Moon
Feb 03  13:56  LAST QUARTER MOON 
Feb 04  02:14  Moon at Ascending Node 
Feb 05  06:39  Antares 6.1°S of Moon
Feb 07  12:09  Moon at Perigee: 365314 km
Feb 08  16     Mercury 0.3° of Mars
Feb 10  07:20  NEW MOON 
Feb 11  17:51  Mercury 5.2°S of Moon
Feb 16  21     Mercury at Greatest Elongation: 18.1°E
Feb 17  02     Mercury at Perihelion 
Feb 17  02:57  Moon at Descending Node 
Feb 17  20:31  FIRST QUARTER MOON 
Feb 18  11:31  Jupiter 0.9°N of Moon: Occultation
Feb 18  18:49  Aldebaran 3.8°S of Moon
Feb 19  06:30  Moon at Apogee: 404475 km
Feb 21  02     Venus at Aphelion 
Feb 21  07     Neptune in Conjunction with Sun 
Feb 25  10:18  Regulus 5.7°N of Moon
Feb 25  20:26  FULL MOON 

As the events above transpire, I will post photographs of some of them at Recent Images.

Astronomical events calendars for complete years and for five time zones are available through the links below.

Time Zones Calendars of Astronomical Events
Greenwich Mean Time 2012 2013 2014 2015 2016 2017 2018 2019 2020
Eastern Standard Time 2012 2013 2014 2015 2016 2017 2018 2019 2020
Central Standard Time 2012 2013 2014 2015 2016 2017 2018 2019 2020
Mountain Standard Time 2012 2013 2014 2015 2016 2017 2018 2019 2020
Pacific Standard Time 2012 2013 2014 2015 2016 2017 2018 2019 2020

For additional years and time zones, see Calendars of Astronomical Events.

The sky events tables were all generated by a computer program I wrote (with THINK Pascal running on a Macintosh G4) using Astronomical Algorithms (Jean Meeus).

Fred Espenak


Pleiades (M45)

Pleiades (M45)

The Pleiades (M45) as imaged with the Takahashi E-180 Astrograph from Bifrost Observatory. For complete details about this image, see Pleiades (M45). Photo copyright 2012 by Fred Espenak.

The Pleiades, M45 or Seven Sisters is one of the best known star clusters in the entire sky. It has been known since antiquity to cultures worldwide and is easily visible to the naked eye on Winter evenings from the Northern Hemisphere. There are references to the Pleiades in the Odyssey, the Bible, and the Quran, and it is also revered in Hindu mythology. Located in the constellation of Taurus, the Pleiades forms a tiny dipper-shaped asterism in the shoulder of the Bull.

This open cluster is composed of extremely hot and luminous blue stars concentrated within a sphere of about 15 light years in diameter. Over 1,000 stars have been identified as members of the cluster, of which about 24 are visible to the naked eye. The faint reflection nebula visible around the brightest stars is an unrelated dust cloud that the cluster is currently passing through.

The age of the Pleiades is estimated to be between 75 and 150 million years making it quite young compared to the Sun’s age of 4.5 billion years. It is traveling slowly in the direction of Orion, but gravitational interactions with other stars in the galactic neighborhood will eventually disperse the cluster about 250 million years in the future.

Early measurements of the cluster’s distance placed it about 135 parsecs (440 light years) from Earth. However, more precise measurements from the
Hipparcos satellite yield a distance of 118 parsecs (385 light years) by using the parallax of stars in the cluster. Although this 14% decrease in distance may not seem significant, it is important because the distances of nearby clusters like the Pleiades are a first step in calibrating the cosmic distance scale. More recent observations from Hubble support the original larger distance so the subject remains unsettled.

Pleiades (M45)

This two-frame mosaic of the Pleiades (M45) was taken the ASA N12 Astrograph from Bifrost Observatory. For complete details about this image, see Pleiades (M45). Photo copyright 2012 by Fred Espenak.

The 18th-century French comet hunter Charles Messier added the Pleiades to his famous catalog as object M45. The original purpose of the catalog was to identify “fuzzy” comet-like objects (star clusters, nebulae and galaxies) to exclude from his true quest for new comets. Today, the Messier Catalog is recognized as the finest collection of bright deep sky objects by amateur astronomers everywhere.

Now it’s time to go outside on some clear, crisp January evening and view the Pleiades with the naked eye, binoculars or even a small telescope.

Fred Espenak