Archive for August 11, 2021

08/11/2021 – Ephemeris – Let’s search for the naked-eye planets for this week, and meteors tonight

August 11, 2021 Comments off

This is Bob Moler with Ephemeris for Wednesday, August 11th. Today the Sun will be up for 14 hours and 13 minutes, setting at 8:54, and it will rise tomorrow at 6:42. The Moon will be 3 days past new tonight.

Let’s search for the naked-eye planets for this week. Venus and the Moon will be close together tonight, with Venus below and right of the waxing crescent Moon by 9:30 tonight. Venus will set at 10:18 pm. With the Moon following at 10:50. By 10 pm, Jupiter and Saturn will be seen low in the southeastern sky. The brighter Jupiter will be easy to spot at that hour. Saturn will be dimmer, but a bit higher and to its right. Tonight and especially in the morning hours tomorrow, the Perseid meteors will be at their peak. These bits of Comet Swift-Tuttle, liberated by the comet’s prior passes in through the warmth of the inner solar system, will flash into incandescence as they enter the Earth’s atmosphere at interplanetary speeds.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.


Venus and the Moon

Venus and the 3-day-old Moon ion evening twilight at 9:45 tonight, August 11, 2021. Created using Stellarium.

Binocular Moon

The Moon as it might appear in binoculars tonight, August 11, 2021, with earth shine on its night side, illuminated by the bright Earth in its sky.
Created using Stellarium.

Jupiter and Saturn in the evening

Jupiter and Saturn in the southeastern sky at 10:30 in the evening tonight, August 11, 2021. Created using Stellarium.

The naked-eye planets as seen in small telescopes

Telescopic view of the bright planets (north up) as they would be seen in a small telescope, with the same magnification, this evening, at 10 pm August 11, 2021. Apparent diameters: Venus, 13.40″; Saturn 18.57″, its rings 43.26″; Jupiter, 49.00″. Jupiter’s moon have a cluster of events in the evening. See below. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge it. Created using Cartes du Ciel (Sky Charts).

                Jupiter's Satellite events
Moon Event EDT (pm-11th, am-12th) UT (12th)
Europa Shadow enters 10:00 pm 02:00
Europa Transit starts 10:25 pm 02:25
Io Eclipse starts 10:41 pm 02:41
Europa Shadow exits 12:51 am 04:51
Ganymede Occultation ends 1:06 am 05:06
Io Occultation ends 1:11 am 05:11
Europa Transit ends 1:12 am 05:12

The above times were determined using Stellarium, and may be off by several minutes.
Shadow events are when a satellite’s shadow is cast onto the face of the planet
Transit events are when the satellite passes in front of the planet
Eclipse events are when a satellite  passes through the planet’s shadow
Occultation events are when the satellite passes behind the planet

Planets and the Moon overnight tonight

Planets and the Moon at sunset and sunrise of a single night, starting with sunset on the right on August 11, 2021. The night ends on the left with sunrise on the 12th. Click on the image to enlarge. Created using my LookingUp program.

Perseid Radiant finder automation

Perseid Radiant finder automation for midnight, August 11th. Created using Stellarium and GIMP.

More on the Perseids on Monday and Tuesday’s posts.