Star Points for August 2010 by Curtis Roelle
Hot Summer Planets

Last month we talked about the summer sun. This month let's prepare for a summer parade of bright 
planets visible to the naked eye. With binoculars you may be able to view all five classical planets.

Since last month's column we've enjoyed – well, experienced – a very hot summer.  We have had 
days with temperatures approaching or reaching the grass withering 100-degree mark. That's 
enough reason to welcome the end of the day and the setting of the sun.  But for amateur 
astronomers, sunset marks the start of the day's most beautiful time: the night.

Following the Summer Solstice in June the sun has been setting earlier each night. Time of sunset 
slips by 40 minutes from 8:20 p.m. in early August to 07:40 p.m. by month's end.  And Venus is the 
first planet to become visible, popping out as the sky starts to darken. 

Venus is easy to spot about 40 minutes after sunset. It will be the bright, white, star-like object low 
in the west-southwest and plainly visible to the unaided eye.  

The hardest of the five to find is Mercury.  I believe you will need binoculars to see Mercury this 
month. You will also need a cloud-free western horizon.  The first thing you need to do is focus 
your binoculars on Venus.  Having them in focus will help in finding Mercury.

At around 9:00 p.m. point your binoculars about 20 degrees to the lower right of Venus, 
approximately the width of two fists at arm's length. You are searching for a star-like object 
considerably fainter than Venus.

An alternative method is to bring your binoculars down to the horizon directly below Venus. Then 
slowly scan to the right several binocular field widths. You are looking for a stellar Mercury.  If you 
don't spot Mercury, move the binoculars slightly upward and scan back to the left. If you don't see 
it at first, repeat this "sweeping" motion as needed until you spot the planet.  

Watch for a couple of minutes to confirm that you're not looking at an airplane instead. Mercury 
will be visible each clear evening for at least the first couple of August weekends. 

This is a good time to mention that if you happen to have a telescope, now is a good time to point it 
at Venus to see its moon-like phase. Due to the current sun-Venus-Earth geometry, Venus appears 
to be a little over half full in early August.

Now that your attention is redirected to Venus, we may continue on to the next two planets.  
Between about 9:15 and 9:30 p.m. Mars and Saturn will come out of the twilight and appear to the 
upper left of Venus. If you're having trouble seeing them, use your binoculars to scan a couple of 
field widths away from Venus. If they're wide-field binoculars, Saturn and Mars will be visible in 
the same binocular field.  Saturn is the brighter, to the upper right of Mars.  Notice how reddish 
Mars appears when viewed side-by-side with Saturn.

From night to night notice how Venus inches up toward the other two. By the second weekend of 
August you might be able to squeeze all three planets – Venus, Mars, and Saturn – into the same 
binocular field as their angular separation decreases. Mars will be to Saturn's left with Venus 
between and below. 

The next planet for our viewing pleasure rises several hours later.  Look for brilliant Jupiter low in 
the east after 11 p.m.  It rises higher each hour until morning twilight. 

I would like to challenge readers to go out during the first two weekends of August and see how 
many of these five planets you can locate. Did you need binoculars to find them?  Once found, 
could you then see them with the unaided eye?  Send me an email and tell me how you did – 
success or failure. 

Next month there will be a chance to easily locate, from your back yard, an even more distant 
planet: Uranus.