July Night Sky
Saturn casts shadow on its ringsBy Larry Mahon
Agate Ridge Observatory
As July begins and darkness approaches you will find Mars about one-third of the way up in the southwestern sky. Saturn will be following Mars by about 24 degrees.
By months end, Mars will have moved two-thirds of this distance toward Saturn leaving them 8 degrees apart. The brightness of both planets will have faded slightly but the view of Saturn will become very interesting.
The angle of its sunshine will be coming from the planet's side making the planet's shadow lie across the ring system.
A small telescope should show this, so as you view Saturn, look for the shadow on the planet's ring system making it appear more three dimensional in your scope.
Two other planets also put on a special show as the month begins. This pairing begins in the morning twilight before dawn.
Venus and Jupiter begin July only 4.8 degrees apart. Venus is at its brightest for the year during the first three weeks of the month at a blazing -4.7 magnitude. Jupiter is less than 1/10th as bright at -2.1 magnitude.
Venus is near the end of its retrograde loop and is parked in the Hyades Cluster while Jupiter is slowly moving eastward causing this closeness to each other. On July 1, Venus is about 12 degrees high and Jupiter is about 16 degrees high at 45 minutes before sunrise.
Venus then starts its eastward motion and by the end of the month they are 13 degrees apart at altitudes of 27 and 40 degrees in mid-twilight.
In telescopes, Jupiter's fully-lit disk grows in size from 34 to 36 arc seconds while Venus's size is decreasing from 45 to 28 arc seconds. On July 15, the waning crescent Moon will be just to the left of this pair an hour before sunrise.
While looking forward to the well-known Perseid Meteor Shower next month, I noticed an article about summer meteor activity in late July and the first few days of August. It reported that 3,875 meteors were video recorded during that period last year.
As we are viewing the sky this summer don't be surprised to see several meteors coming from the southern sky. I am sure that we will see several during the star party on the top of Round Butte on July 20, or if bad viewing weather that night, on the 21.
It is also interesting to note that while we in the northern hemisphere are receiving very warm weather, the earth reaches aphelion on July 4. This is our greatest orbital distance in space from the Sun.
It will be 94,506,000 miles away from us. The direct sun light is pretty hot at that distance today. How hot would it be if the Sun were at perihelion, it's closest to us? Happy viewing.