Supermoon Fun / Mars-Spica Conjunction Tonight / Venus Visits Mercury At Dawn

Passing clouds create a colorful corona around last night’s full moon. Credit: Bob King

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.

A delicate display of crepuscular rays radiates across the sky above a cloud-shrouded moon. Credit: Bob King

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.

Last night’s supermoon shines back from a mobile phone. I took the picture by holding the phone’s camera lens directly over the eyepiece. Credit: Bob King

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.

Mars (top) and Spica last night July 12. The difference in color between the rusty planet and blue-white star was very easy to see. Mars will remain near the star the next few nights but change its position like the hour hand on a clock. Credit: Bob King

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.

Venus and Mercury shine together low in the northeastern sky during morning twilight the next couple weeks. This map shows the view tomorrow morning 45 minutes before sunrise. Venus will be about 10 degrees (one ‘fist’) high, Mercury half as much. Source: Stellarium

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.

6 Responses

  1. Quick note to confirm that Venus and Mercury are indeed visible in the pre-dawn hours, although Mercury is a bit challenging here with the naked eyes (but not with my 20X80 binocs) due to light smoke from forest fires in the far north, over 1000 miles away. Temperature hovering around the 100°F (38°C) mark with very low humidity makes my area pretty vulnerable at this time. At least there is no lightning in the forecast for the next week. Hopefully it won’t affect the upcoming Mt. Kobau star party in 2 weeks ( )

    1. astrobob

      Thanks Paul. I had no idea it got so hot where you live. We often get forest fire smoke around here in summer from as far as the Northwest Territories but usually from Ontario. It can completely alter the sky transparency for days … and nights.

  2. Edward M. Boll

    I know this may be early, but so far I am encouraged that the possible bright comet of US 10 Catalina for late next year is brighter than normal.

  3. Edward M. Boll

    I had not seen Mars for a while, but was surprised and impressed at how close it was to Spica last night. I saw the 2 before I saw that you had posted on the conjunction.

  4. Giorgio Rizzarelli

    Saw Mars-Spica, indeed the color contrast was evident at most at twilight.

    Also seen Mars in scope. Now near quadrature, the 87% phase (it will not get less than that) appears more toward quarter than what one could expect from Mars. Few detail is still visible, like polar cap and some terrain (the planet was low hence seeing bad, so possibly one could see more detail)

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