07/21/2020 – Ephemeris – Saturn’s opposition yesterday and Comet NEOWISE update

This is Ephemeris for Tuesday, July 21st. Today the Sun will be up for 15 hours and 2 minutes, setting at 9:20, and it will rise tomorrow at 6:18. The Moon, 1 day past new, will set at 10:26 this evening.

The planet Saturn passed opposition from the Sun yesterday and is its closest to the Earth at 837 million miles (1,348 km). Saturn’s apparent size doesn’t change much in telescopes over the year because its distance only changes plus or minus 10% over the year and week and a half or so of its synodic period, the period between successive oppositions. Closer to the Sun Comet NEOWISE is approaching and is about to pass above the rear paw of the Great Bear Ursa Major below the bowl of the Big Dipper which marks the bear’s hind end. The comet is higher in the sky than it was last week, but it is fading. Moonlight will begin to affect the comet later this week, so binoculars will definitely help in spotting it.

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

Addendum

Comet NEOWISE finder chart for tonight July 21, 2020 at 11 pm or about an hour and a half after sunset. Created using Stellarium.

Photograph of Comet NEOWISE taken Sunday night at midnight July 20, 2020 EDT. The direction of the bright dust tail of the comet leans a bit to the right. The barely visible thin blue ion tail is pointed more directly away from the Sun. The slower escaping dust tail shows the sideways component of the comet’s motion relative to the Sun.   Credit Bob Moler. Camera: Canon EOS REBEL T5, f/3.5, 15 seconds, fixed camera (not tracking), ISO 6400, Focal Length 18mm.

Saturn opposition diagram using the JPL Small-Body Database Browser. I tried to align the Z-axis (vertical) with the Earth on the blue orbit and Saturn on the yellow orbit so the Earth is directly between the Sun and Saturn.