January Sky Notes
A Load of Bull ... Taurus
The January night sky is a delight to explore for observers of all abilities. The southern aspect is strewn with stellar luminaries, star clusters and nebulae, with a good number of showpiece objects visible to scrutinise. Of the plethora of imposing and important star patterns ranged across the south, some of which have been revered by civilisations for thousands of years, the great bull, Taurus leads the way.
Identified by the starry ‘V’ asterism we call the Hyades star cluster, the eastern tip of the Bull’s head is marked by the chief star in Taurus, the ‘eye of the bull’ Aldebaran. In reality it is not a true member and lies at half the distance (65 light years) of the true Hyades members. The Hyades are the second closest stellar cluster to us and a fine site through binoculars, but are overshadowed by another open cluster located ahead and above the head of Taurus, their half sisters the Pleiades or seven sisters.
This cluster is a breathtaking spectacle when viewed through binoculars or low power telescope, appearing like beads of dew on a frosty web. The cluster lies around 400 light years light years away and is probably less than 120 million years old. Although popularly termed the Seven Sisters, only six stars are easily visible to the naked eye. Binoculars show dozens of stars, the entire cluster contains a hundred or so members.
Marking the left horn of the bull is Alnath, being common with the right foot of Auriga, the Charioteer. Close by the bull’s right horn, Zeta Tauri, resides one of the heavens' most celebrated and intensely studied objects, the remarkable Crab Nebula. This marks the location of a stellar explosion or supernova seen from Earth in AD 1054 and bright enough to be visible in daylight for several weeks. The still expanding nebula remnant lies 6000 light years away. Irish astronomer Lord Rosse gave the nebula its name in 1844 because he thought its shape resembled a crab when seen through his large telescope. Through smaller instruments the nebula appears as a misty smudge of light, at the heart of which lies the remnant of the once mighty star's core, a spinning neutron star, a super dense, incredibly small object a few tens of miles in diameter spinning 30 times per second. Since its discovery in 1968 the Crab pulsar has become one of the most studied objects (across all wavelengths) in the entire sky, but to see it visually requires a very large scope and imaging device. Still, binoculars will show the nebula from a dark location. Choose a clear moonless night at the end of the month and have a go!
Have a Happy New Year – and let’s hope for a few clear nights!
Mark Dawson,
Whitby & District Astronomical Society
For more information about Whitby & District Astronomical Society see: www.whitby-astronomers.com
