The moon coaxed many of us out for a look last night. We had clear if hazy skies in my town which made for a striking display of lunar crepuscular rays. Lunar what? If you’ve ever seen sunbeams poking through clouds in the afternoon or evening, you’re looking at crepuscular rays. Crepuscular comes from the Latin word for ‘twilight’ as the beams are often noticed during early evening hours around sunset.
Bright rays shining through gaps in the clouds alternate with shadows cast by other clouds to form a spreading fan of light and dark columns. The dustier or smokier the air, the more vivid the crepuscular display. Notice how they appear to converge on the moon. This is an optical illusion. The rays are perfectly parallel just like endless rows of beans on a farm that appear to merge together in the distance.
Many of us like to take pictures of the moon through a telescope using nothing more than a mobile phone. If you’ve tried this, you know how tricky it is to hold the phone camera in the right spot over the telescope eyepiece. It takes a few tries, but the results can be remarkable. Phones do well on bright celestial object like the planets, moon and sun (with a safe filter). Despite what some ads might tout, phones can’t yet record fainter things like galaxies, nebulae and the like.
Orion Telescopes makes an adaptor to hold a phone securely over the telescope. While it gets mixed reviews, you might want to consider it if you don’t want to invest in a separate camera but would still like to create an album of your own astrophotos.
I know we’ve all been moonstruck the past few nights, but did you happen to notice how close Mars and Virgo’s brightest star Spica have become? Last night they were separated by only 1.5 degrees; tonight they’ll be in conjunction a squinch closer at 1.3 degrees. Watch for the duo in the southwestern sky near the end of evening twilight.
Mars moves eastward and soon departs Spica en route to its next notable appointment, a conjunction with Saturn on August 25. Have you been up at 5 a.m. lately? Me neither. But my crystal ball a.k.a. Stellarium program tells me that Venus and Mercury are playing tag an hour before sunrise in the eastern sky.
Mercury reached greatest elongation (distance) west of the sun yesterday and now appears about five degrees high in the northeast some 45 minutes before sunrise. Look for it about the same distance below brilliant Venus. This is a good apparition of Mercury, and having Venus nearby makes it easy to spot.
The swiftest-moving planet will hang near the goddess planet for the next two weeks, all the while growing in brightness as its phase fills out from crescent to full.