This week we’ll focus on the planets.
The brightest planet in the evening sky is the king of the planets, Jupiter. You’ll see Jupiter low in the southeast as darkness falls, and high in the south around 1 a.m. No star or other planet is brighter.
This is a good week to look at Saturn through a telescope because it’s at its highest, 1/3 of the way up the southern sky, at about 10 p.m. By then the ground has cooled from the heat of the day and atmospheric turbulence is reduced. Notice the angle the rings make to our line-of-sight.
Our earth is tilted on its axis by 23½ degrees; Saturn is tilted 27 degrees. Since Saturn orbits the sun in almost 30 earth-years (which equals 1 Saturn-year), the tilt that we see from earth ranges from 27 degrees (when they’re at their widest open) to 0 degrees (when they’re edge-on); at present the tilt is 14 degrees and decreasing. We now see the northern hemisphere of Saturn and the north side of the rings.
You’ll need a telescope with at least 30-power to see the rings, and when you do see them make a sketch of their orientation.
Compare in only three years when they’re nearly edge-on. In three more years (2028) they’ll be back like they are now, but we’ll then be looking at their south side. Wikipedia can give you the details I don’t have space for.
On Wednesday, Saturn is 7 degrees to the upper right of the moon; and on Oct. 10, Jupiter is 5 degrees to the upper right of the moon.
On Thursday the nearly-full moon sits midway between Jupiter and Saturn. That’s midway as seen on the dome of the sky, but of course they’re at vastly different distances from us and from each other. Think of their distances in terms of the speed of light: by light the moon is 1¼ seconds away, Jupiter is 33 minutes away, and Saturn one hour 17 minutes away. And of course the stars “near” them are many light years distant. For example, the star just below the moon, with the unusual name Skat (Arabic for “shin”), is about 110 light years away.
The third planet visible tonight is Mars, which rises before midnight. The earth is catching Mars on an inside orbit, so it’s slowly growing brighter as we approach it. Mars is in Taurus, where it’s equi-distant from the orange stars Aldebaran and Betelgeuse and is slightly brighter than either (only the white star Sirius is brighter than Mars). Mars is at it’s highest at 6 a.m. when it’s due south and nearly overhead.
Mars is almost close enough to see to see its major surface features through an excellent telescope. Check this website.
From roughly 11 p.m. until 3 a.m. you can see these three planets at the same time.
You might spot elusive Mercury 45 minutes before sunrise, when it will be only about 8 degrees above the horizon, but compliment yourself if you do.