On Thursday, December 8, the Sun, Earth, and Mars are perfectly aligned in space.
Being at its minimum distance from Earth and frontally illuminated by the Sun, the red planet appears super bright.
At dawn on the 8th, Mars will be hidden by the Moon for 46 minutes.
Alignment
After sunset on Thursday the 8th, if the atmosphere allows it, we will be able to see Mars rise in the east.
At the moment it is aligned with the Sun and the Earth, it is the geometric configuration that astronomers call "opposition" because the planet, seen from the Earth, is in a situation completely opposite to the Sun. That is to say: Mars is rises when the Sun goes down and goes to bed when the Sun rises.
Mars is 1.5 times farther from the Sun than Earth and takes 1.88 times longer to complete its orbit.
This makes the oppositions of the red planet happen every 2.13 years.
The previous opposition to this one took place on October 13, 2020 and the next one will take place on January 16, 2025.
the opposition of mars
Since the Martian orbit is slightly more elliptical than the Earth's, the Earth-Mars distance is different at each opposition.
On this occasion, Mars will approach 81.4 million kilometers away (for orientation, remember that the Earth-Sun distance is 150 million kilometers).
In the opposition of the year 2020, Mars approached 62 million kilometers.
And in the summer of 2018, Mars was located just 59 million kilometers from Earth, offering us a magnificent spectacle in the summer sky.
This time the red planet will not shine as brightly as then and its apparent diameter will be smaller, but even so, the reddish glow of Mars shines splendidly these days among the bright stars that surround it, such as those in the constellations of Taurus and Orion.
retrograde motion
If we look at Mars day after day, we will see that it is now in its retrograde cycle, it appears to be moving west through the constellation Taurus.
The point of opposition marks the center of the path of this retrograde movement that will end on January 12, 2023, when it will resume its direct movement to the east.
As the accompanying diagram illustrates, retrograde motion, which has plagued geocentric astronomers for centuries, is a result of the combined orbital motions of Earth and Mars around the Sun.
Retrograde motion of MarsNASA
As we said, Mars rises when the Sun goes to bed. Throughout the night it gradually rises above the horizon to culminate in the meridian around 1 in the morning.
This is the best time to observe it.
If you have a small telescope you can observe some detail of its surface, with different colored filters you can see different details of its topography, its icy clouds or even its polar caps.
Concealment
In these days another opposition also happens: that of the Moon that is in the full moon.
Since both stars are in the opposite direction to the Sun, it turns out that both the full moon and Mars look very close in the sky.
In fact, they are so close that there will be an occultation of Mars by the Moon in the early morning of December 8.
Simulation of the occultation of MarsStellarium/RB
From Spain, the occultation will be seen near its sunset, when the stars will have already descended to low elevations.
Specifically, from Madrid, the immersion of Mars behind the Moon will take place at 6:21, peninsular time, at 24 degrees of elevation.
And the emersion will be at 7:07, at 16 degrees above the horizon.
Therefore, to observe this beautiful spectacle, which lasts 46 minutes, it is essential to get up early (or stay up late the day before), have a sky clear of clouds and look for a horizon to the west free of obstacles such as trees or buildings. .
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Rafael Bachiller is director of the National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.
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