And the first star... is a planet
Diehard powderhounds may have been disappointed over the past week, but the fabulously clear skies provided the rest of us with pretty good compensation. Add the full moon (which occurred on the 30th), and the scene was perfect.
While most people enjoy watching the moon (especially when it’s full), lots throw up their hands after learning the first couple of constellations. Pity. There’s lots to reward a little bit of time spent learning more.
You don’t need the Hubble telescope to stargaze in Whistler, just some interest and perhaps the occasional look through a pair of binoculars or a friend’s hobby telescope. A few tips will also help direct your gaze.
For example, how do you identify the bright star that rises at around 7 p.m. and is high in the sky by midnight? Here’s a hint: it’s not a star, it’s a planet. How can you tell? Stars twinkle at least a little; planets don’t. The twinkling is caused by the diffraction of the stars’ pinpoint beam of photons through the turbulent atmosphere. Planets are close enough to present a disk (although the disk is too small to see with the naked eye) and thus a broader beam of photons that is not disrupted in the same way by the atmosphere.
This week’s first mystery star is actually Jupiter, currently the brightest object in the night sky other than the moon. With a pair of 7x50 binoculars you can probably spot three or four of its moons: Io, Europa, Ganymede and Callisto. They will look like stars forming a straight line near Jupiter’s brilliant disk.
Now stretch your right hand overhead with arm straight and fingers spread. Place your thumb near Jupiter and rotate your hand so that your little finger is pointing west. Near your little finger you will see two moderately bright stars, one of which is twinkling and the second of which is shining with a steady, and slightly yellowish, light. This is Saturn, the ringed planet and our second mystery star. The other star is Aldebaran, the eye of Taurus the bull, located about 65 light years from Earth. Aldebaran is a massive red giant with a diameter 50 greater times that of our sun and shining over 300 times brighter.
We generally think of stars as shining with a white light but in actuality they have colours ranging from blue through to white, yellow and red, depending on their surface temperature. We have difficulty seeing these colours because our eyes’ colour receptors do not work well in dim light. If you look carefully, however, you can see colour in some of the brighter sky objects. Compare Jupiter, Saturn and Aldebaran with other stars in the sky. (You will find this easier if you allow your eyes to adapt to the dark for at least five minutes and ideally 20 minutes). Jupiter is pearly white, Saturn is yellow and Aldebaran, the red giant, is – surprise – distinctly reddish in colour.
And speaking of the dark, watch this column for an upcoming article on the scourge of light pollution, a menace that threatens our enjoyment of the Whistler night sky.
Website of the week: Check out Sky & Telescope Magazine at http://www.skypub.com .
There won’t be a bird walk this Saturday, but monthly counts will resume on the first Saturday of each month starting on Feb. 2 (and always meet at the base of Lorimer Road at 8 a.m.). Contact Michael Thompson for details.
Written by: Don Brett