■ Yesterday evening, the Moon shone close to Jupiter. Now it’s Saturn’s turn to pair up with the Moon, as shown below.

All week, as the Moon steps farther east, the two giant planets continue shining nearly level in the south at dusk. They tilt to the right as evening advances. They set in the southwest around midnight.

Moon under Jupiter and Saturn, Sept 24-25, 2020
The Moon is 1.3 light-seconds from Earth, but Jupiter is currently 40 light-minutes distant and Saturn is 80 light-minutes. As for the stars? The light from that top one in the Teapot’s handle, bluish-white Nunki, has been traveling for 230 years to shine on you tonight.


■ Now the waxing gibbous Moon shines inside the dim, boat-shaped star pattern of Capricornus, left of Saturn and Jupiter. Look to the Moon’s lower left a little farther to spot Fomalhaut, the Autumn Star, slowly gaining altitude now that autumn is here.


■ Arcturus shines in the west these evenings as twilight fades out. Capella, equally bright, is barely rising in the north-northeast (depending on your latitude; the farther north you are the higher it will be.) They’re both magnitude 0.

Late in the evening, Arcturus and Capella shine at the same height in their respective compass directions. When will this happen? That depends on both your latitude and longitude.

When it does, turn around and look low in the south-southeast. There will be 1st-magnitude Fomalhaut at the same height too — exactly so if you’re at latitude 43° north (from Boston to Buffalo, Milwaukee, Boise, Eugene). Seen from south of that latitude, Fomalhaut will appear higher than Capella and Arcturus are. Seen from north of there, it will be lower.

■ Jupiter’s Great Red Spot should transit Jupiter’s central meridian around 8:32 p.m. Eastern Daylight Time. Later, at 10:41 p.m. EDT, Io will reappear out of eclipse from Jupiter’s shadow. Watch for it to emerge into sunlight over a couple of minutes a little to the planet’s east.


■ Cygnus the Swan floats nearly straight overhead these evenings. Its brightest stars form the big Northern Cross. When you face southwest and crane your head up, the cross appears to stand upright. It’s about two fists at arm’s length tall, with Deneb as its top. Or to put it another way, when you face that direction the Swan appears to be diving straight down (which real swans never do).


■ Jupiter’s Great Red Spot should transit Jupiter’s central meridian around 10:11 p.m. EDT. An hour and ten minutes later, Io begins crossing Jupiter’s face. FULL STORY HERE