December 17, 2022: The thick morning crescent is near Porrima in Virgo this morning. An evening display of the five bright planets is beginning to form.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:13 a.m. CST; Sunset, 4:21 p.m. CST. Check local sources for sunrise and sunset times for your location.
Jupiter’s Great Red Spot’s transit times, when it is in the center of the planet in the southern hemisphere: 2:50 UT, 12:45 UT, 22:41 UT. Convert the time to your time zone. In the US, subtract five hours for EST, six hours for CST, and so on. Use a telescope to see the spot. Times are from Sky & Telescope magazine.
This is the 50th anniversary of the last Apollo lunar mission – Apollo 17. On December 17, 1972, on the way back to Earth, Ronald Evans left the command module for a 65-minute excursion to retrieve film canisters and data film from the experiment bay in the service module.
Summaries of Current Sky Events
Here is today’s planet forecast:
Morning Sky
An hour before sunrise, the thick crescent moon, 39% illuminated, is about halfway up in the south-southeast and 1.5° to the right of Porrima, also known as Gamma Virginis. The moon covers or occults the star for sky watchers in Hawaii, beginning after 3:30 a.m. HST. This is the last lunar occultation of a bright star for the year.
At the waning crescent phase, the moon is beginning to show earthshine, reflected sunlight from Earth’s oceans, clouds, and land. This light gently illuminates the lunar night. A binocular or spotting scope makes the view clearer. A tripod-mounted camera with a short time exposure captures the scene.
The morning sky is without a bright planet, although Mars is barely above the western horizon at this hour. The view of the solar system turns to the evening sky, where a five-planet display is beginning to form shortly after sunset.
Evening Sky
Mercury and Venus are still a challenge to see. At thirty-minutes after sundown, Venus is less than 5° up in the southwest, about 8° to the right of the southwest point. At this time, the planet is likely visible without a binocular’s optical assist, but one might be needed to initially spot the planet.
Mercury is 5.9° to the upper left of Venus. Both fit into a binocular field of view. Can you see Mercury without the binocular.
Mercury reaches its greatest angular separation from the sun on the 21st. Beginning on the 24th, the crescent moon joins the scene. The two planets and the lunar crescent are low in the western sky at 45 minutes after sundown. If you’ve not spotted Venus, begin to look for a location with a clear horizon to the southwest, so that you can look for the five planets simultaneously for about four evenings. After that, Mercury is still present, but its brightness begins to fade quickly.
Sky watchers at more southerly latitudes have a better view of the two planets, higher in the sky and the worlds can be found a little later in a slightly darker sky
At this time interval after sundown, Saturn is not visible about 35° to the upper left of Mercury.
The Ringed Wonder is easily visible by one hour after sunset. It is about one-third of the way up in the south-southwest. It is moving eastward against stars in eastern Capricornus. This evening Saturn is 1.6° from Nashira. The planet passes 1.3° from the star on the evenings of the 27th and 28th. Follow the planet’s path each clear evening with a binocular.
Bright Jupiter is nearly 40° to the upper left of Saturn. It is the brightest star in the sky this evening, especially after Venus sets. Being farther eastward and away from the glare of the western early evening twilight, Jupiter is likely visible when looking for Venus and Mercury.
Jupiter is moving eastward against a dim starfield in Pisces, much dimmer than those in Saturn’s celestial location this evening.
Mars, also likely visible low in the east-northeast when Mercury and Venus are visible, is somewhat higher in the sky at one hour after sundown. The planet is 8.4° to the upper left of Aldebaran, the brightest star in Taurus.
The Red Planet continues to retrograde in front of the Bull. It passes Aldebaran again on the 26th and ends its retrograde on January 12. Mars passes Aldebaran for the third and final conjunction on January 30th.
For the next 90 minutes or so, the three bright outer planets are easy to see simultaneously as they shift farther westward. Look for them before Saturn disappears behind obstacles in the southwest.
Tomorrow morning, Mars might be visible very close to the horizon in the west-northwest. For practical observations, it has disappeared into the thicker layers of atmosphere near the horizon.
Meanwhile, the crescent moon is near the star Spica about an hour before daybreak.
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