Archive for September 16, 2020

09/16/2020 – Ephemeris – Let’s look at a the naked-eye planets for this week. Plus thoughts on phosphine in Venus’ atmosphere

September 16, 2020 Comments off

This is Ephemeris for Wednesday, September 16th. Today the Sun will be up for 12 hours and 27 minutes, setting at 7:50, and it will rise tomorrow at 7:24. The Moon, 1 day before new, will rise at 7:20 tomorrow morning.

Let’s look at a the naked-eye planets for this week. Jupiter and Saturn are both low in the southern sky at 10 pm. Jupiter is the very bright one. To the left of it will be the somewhat dimmer Saturn. They are now seemly to close a tiny bit since Jupiter is resuming its eastward motion, and they will cross paths in December. Jupiter will set first at 1:37 tomorrow morning with Saturn following at 2:19. The next planet visible will be Mars which will rise at 9:15 pm. Its now down to 41.3 million miles (66.6 million kilometers) away, as the Earth slowly overtakes it at the rate of about 2.1 million miles (3.1 million kilometers) the last week as the Earth begins to pull abreast of it. Brilliant Venus will rise at 3:42 am as it retreats toward the Sun.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Evening planet animated finder

Planets visible at 10 pm or about 2 hours after sunset with the zodiacal constellations tonight September 16, 2020. Click on the image to enlarge. Created using Stellarium and GIMP.

Morning planet finder animation

Mars, Venus and the zodiacal constellations and Orion at 6 am or an hour and a half before sunrise tomorrow morning September 17, 2020. Click on the image to enlarge. Created using Stellarium and GIMP.

Telescopic Planets

The planets as seen in a telescope (north up) with the same magnification for the night of September 16/17, 2020. Times of the display are: Jupiter and Saturn, 10 pm; Mars, Midnight; Venus, 6 am. Apparent diameters: Jupiter, 42.31″; Saturn, 17.59″, rings, 40.96″. Mars, 21.24″, and Venus 17.09″. Mars also displays an enlargement showing surface detail. The ” symbol means seconds of arc (1/3600th of a degree.) Created using Cartes du Ciel (Sky Charts).

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on September 16, 2020. The night ends on the left with sunrise on the 17th. Click on the image to enlarge. Created using my LookingUp program.

Breaking planet news

Yesterday there were a rash of posts on social media and other sources to the effect “Is there life on Venus?” This was due to an article released in Nature Astronomy that the compound phosphine was discovered in the Venusian atmosphere. Phosphine (PH3) on the Earth, at least, is mostly produced by life processes. I’m still absorbing all of this so check out articles by Dr. Phil Plait (The Bad Astronomer) and Steven Novella (Skeptic’s Guide to the Universe) for less technical takes on the discovery.

Venus is the subject of two of the four proposed discovery program missions that NASA announced this past June. one of them DAVINCI+ will be looking at the atmospheric chemistry and might get a boost and some tweaks due to the phosphine discovery. DAVINCI+ will drop through the atmosphere. The best mission for this would be a balloon floating in the Venusian atmosphere above the sulfuric acid clouds. The Russians did it in 1986. Anyway any mission to Venus is many years away.

I’ll have more for the Ephemeris program itself when I know more.