December 7, 2022: Mars is at opposition – in the opposite direction from the sun – this evening. The Full moon covers Mars in a rare occultation on opposition night.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:05 a.m. CST; Sunset, 4:20 p.m. CST. Check local sources for sunrise and sunset times for your location.
Not until 2059 will Mars and the Full moon perform a precise dance that is timed as closely as they do this evening. Mars is covered or occulted by the Full moon and is at opposition with the sun within 2.5 hours.
There are no celestial chimes that sound. The near-coincidence of these two events is interesting to note. Sky watchers sometimes converse about the passing of times between celestial events such as solar and lunar eclipses as well as close oppositions of the planets in the same manner that sports fans reminisce about their favorite teams’ championship runs, travelers note their trips, and families reflect on special events. This is one of those memorable celestial events to help mark the passage of time.
The moon occults or covers Mars, beginning at 9:10 p.m. CST for Chicago. This event is easily visible across the US – except the Southeast – Canada, Greenland, western Europe, and northwest Africa.
Mars is the second brightest star in the evening sky, following bright Jupiter. Even with the moon’s bright glare, Mars is visible next to the lunar globe. A binocular or spotting scope is helpful to see the planet disappear and reappear. From Chicago, the bright moon begins to cover Mars at 9:10 p.m. CST. The Red Planet emerges from behind the lunar orb at 10:04 p.m. During the 56 minutes, the moon rises higher in the east-southeast, appearing nearly two-thirds of the way up in the sky.
See this link for predicted disappearance and reappearance times for cities across the region where the occultation is visible. Times on the table are in UT, Universal Time. Subtract or add time depending on your time zone. Subtract five hours for EST, six for CST, and so on. The table is long and US cities are near the bottom of the disappearance list and the reappearance times.
Mars is at opposition at 11:34 p.m. CST. Earth is between the sun and the Red Planet so they are in opposite directions in the sky. On opposition night as the sun sets, Mars rises in the east. The planet is south at midnight, while the sun is south at noon. Mars sets in the western sky as the sun rises in the east.
There is a Mars occultation two days from the planet’s opposition in 2025. The next time this occurs with an opposition and occultation within the same twenty-four-hour period is 2059. There’s more in the background section later after the planet forecast.
Here is today’s planet forecast:
Morning Sky
An hour before sunrise, the bright moon is near the horizon in the west-northwest, with Mars 9.3° to the upper left of the lunar orb. Notice the separation of Mars and the moon this morning compared to this evening.
During the daytime in the western hemisphere, the moon closes in on the Red Planet. At this hour, Mars is the only bright planet in the sky.
SUMMARIES FOR CURRENT SKY EVENTS
Evening Sky
Venus and Mercury are slowly moving into the evening sky. Venus sets over 40 minutes after sundown, with Mercury following about 10 minutes later. We’ll begin looking for them at 30 minutes after sundown.
An hour after sunset, the Full (Cold) moon is low in the east-northeast, 2.0° to the upper right of Mars. The occultation is a few hours away.
Meanwhile, bright Jupiter is nearly halfway up in the south-southeast, moving slowly eastward in front of the stars of Pisces, whitewashed by the moon’s glare.
Saturn is about one-third of the way up in the south-southwest, traveling eastward against a starfield in eastern Capricornus.
Less than 2.5 hours after sundown, the three planets and the moon are lined up along the arc of the ecliptic.
Background
The moon passes the planets each month. Its orbit is tilted compared to the ecliptic – the plane of the solar system. This tilt makes solar and lunar eclipses infrequent events. The bright planets are visible very close to the imaginary ecliptic line. When the moon crosses the ecliptic, twice a month, it can cover anything in the ecliptic plane, including the sun and planets. Since the sun and moon appear to be nearly the same size, we can see a solar eclipse when the moon is at its New moon phase.
When the moon crosses in front of a planet or a bright star, this eclipse is called an occultation. The moon occulted Mars twice this year and predicted to cover the Red Planet five times during 2023. Tonight’s occultation makes the third of the year.
The places where the moon crosses the ecliptic are called nodes. The nodes slip along the ecliptic in a cycle lasting nearly 19 years. While the nodes move, the planets seem to move eastward along the ecliptic and sometimes move westward. Seemingly, it’s like a cat attempting to catch a mouse, except the moon continues to step eastward, while the distant planets move eastward or westward. The cat cannot turn around to pounce on the elusive mouse.
While the moon mainly misses the planets each month, these groupings make attractive sights in the sky.
A few hours after the occultation this evening, Mars is at opposition. Earth is exactly between the planet and the sun. Again, there is no celestial music. The event could be seen in Mars’ position against the starfield with a telescope and an eyepiece to measure the angular separation between the planet and stars in the same field of view.
How frequently is Mars at opposition and occulted by the moon on the same evening or nearly so? The timing of a Mars opposition and a lunar occultation of the Red Planet occurring 24 hours on either side of the opposition is rare. Why 24 hours? Because we have to make a decision about the time interval. So, essentially a 48-hour window has been chosen, centered on the Martian opposition.
A search was conducted for a Mars opposition with a lunar occultation of that planet within that 48-hour window that is visible from the US. The next time this occurs for Chicago sky watchers is with the Mars opposition on February 26, 2059, at 11:25 p.m. CST (if standard time exists during that year). The lunar occultation begins the next morning at 3:40 a.m. CST, lasting 65 minutes. This occurs with the moon in the western sky. This event is higher in the sky for sky watchers farther westward.
During 2025, at the next Martian opposition (January 15, 8:32 p.m. CST), the moon occults the planet two days earlier, beginning at 7:51 p.m. CST in Chicago, a day too early to fit the definition, but another spectacular event, nonetheless.
During 2027, the moon nearly occults Jupiter on February 19th, the night of the Mars opposition, from Chicago. The occultation is visible from the southeast Pacific Ocean basin. The next evening, the moon rises in a penumbral eclipse. Mars, Jupiter and the Full moon fit into a region that you can cover with your fist, extended to arm’s length.
It is not unusual to see the Full moon with Mars near opposition when the planet is bright in the sky. At the March 25, 2029, opposition, the Full moon is nearby on the 28th and 29th.
At the May 4, 2031, Mars opposition, the moon has another penumbral lunar eclipse three nights later.
There are interesting groupings of the moon and planets each month. Return to these articles and the associated podcasts for upcoming events.
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