Western Slope Skies 5/24/2013

May 24, 2013

This week, just after sunset, we can see an amazing grouping of  planets in the western sky.  From May 24 until May 29, Venus, Jupiter, and Mercury will fit within a 5 degree circle – less than half the width of your fist held at arm’s length!   On May 26 these planets will be within 2 and one half degrees of each other – only half the apparent distance between the pointer stars of the Big Dipper!    

You will need a place that has a flat northwest horizon.  Start looking for the planets right after sunset, as all 3 planets will set about an hour later.  Remember, never look at the sun directly, especially with binoculars – severe eye damage will result.

Twilight glare will make it hard to see the planets at first, but as the sky darkens, Venus, then Jupiter, and finally Mercury will become visible.  Binoculars may help you spot the planets initially, but slowly they will become easier to see unaided.              

Mercury and Venus have just recently passed behind the sun and are now becoming visible in our evening sky.  Jupiter, which has been visible all year, is now starting to pass behind the sun from our viewpoint on Earth. 

Although Venus, Jupiter, and Mercury now appear close together from our perspective, they are actually far apart in space.   On May 26, Mercury is 108 million miles from Earth, Venus is 153 million miles from Earth, and Jupiter is a whopping 564 million miles from us.    Venus appears very bright because it is has highly reflective clouds and is about the same size as Earth.  Jupiter is bright because it’s huge, 11 times Earth’s diameter.  Mercury is the faintest of this trio, because it’s the smallest planet and has fairly dark surface.     

“Western Slope Skies is produced by members of the Black Canyon Astronomical Society, and hosted by Art Trevena.