July 2016

July 2016 provides the chance to see five naked eye planets in one viewing session right after the sun goes down. Two of them will be close to the horizon as darkness sets in. So they won’t be up long.

Let’s start with Jupiter. The big planet will move slowly below the belly of Leo the lion all month. A crescent moon in the neighborhood on the 9th and 10th will help you identify it. Northern hemisphere viewers can find it in the southwest at dusk. That close call with the moon will be a cover-up in some places. You’ll need to be in the South Sea or Antarctica south of Australia.

In the south you will find Mars and Saturn. Mars is moving eastward from Libra to Scorpio while Saturn stays in pretty much the same spot west of the claws of Scorpio. The ringed planet is actually moving westward very slowly. You can tell if you watch from evening to evening. A gibbous moon will be north of Mars on the 15th and north of Saturn on the 16th.

Venus and Mercury will be trickier, but not impossible. You may need to go away from your own yard to someplace where you have a horizon not impeded by buildings, trees, mountains, or other things in the way of your view. A pair of binoculars may help you determine if you’re looking at one of the planets or a distant light or airplane.

Venus is easiest to see at first. But you won’t have long after sunset. It sets just a half hour after the sun on the 1st. Keep watching from evening to evening and you’ll gain a few minutes of viewing time while also observing the planet to be moving to the left. You should also start looking below and the right of very bright Venus for a dimmer object that’s a little higher each night. That would be Mercury. By the 15th, you’ll see Mercury to the right of Venus. Both will set about 45 minutes after the sun. After that, Mercury is above Venus for a few evenings. Then, in the last days of July, Mercury is nicely placed between Venus and Regulus, the bright star in Leo.

The end of July will be the best time to see all five naked eye planets in the sky at the same time. If you want to throw in the moon as a bonus, look on the 20th when the moon is almost full. It will be rising while Mercury is setting. There’s a risk, however, that you’ll need to see Mercury with binoculars because the sun is still close below the horizon.

Mars has its southward equinox on the 4th.

Lunar perigee will occur on the 1st and 27th. Apogee will be on the 13th.

Mercury is at perihelion on the 2nd, Earth is at aphelion on the 4th, and Venus is at perihelion on the 11th.

If you have a very dark location and a big enough telescope, this is a good month to see Pluto. It’s at opposition on the 7th. There won’t be any interference from moonlight.

Pretty much all of Central America is well placed for an occultation of Aldebaran on the morning of July 29.


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