Please set your alarm, Mars will go retrograde at the end of the month!

October 30, 2022: The red planet Mars begins to move retrograde tonight. Compared to the constellation Taurus, the planet's eastward direction stops and begins to move westward, or retrograde.

Description - October 30, 2022: Mars above the horns of Taurus before dawn

Although Jupiter is bright throughout much of the night, this year's fall spectacle occurs on December 7.

Mars 2022?

During this season, Mars appears with many bright stars. Mars rises in the east-northeast 2.5 hours after sunset. At night, it appears higher in the sky; in the morning twilight, it hangs high above the horns of the Bull, Elnas and Zeta Taurus in the west-southwest. Skywatchers in cities and suburbs may need binoculars to see Taurus. Mars is easily visible. Only Sirius is brighter.

For the past three months, Mars has been moving gradually eastward in front of the constellation Taurus. Its movement is easy to see. Recently, however, its eastward movement has slowed down, and on several mornings, it was almost in the same position as the southern corner of Zeta Taurus.

The motion of a planet against the background of stars is a combination of the motion of the Earth and the planet's orbit around the Sun. In our view, they appear against the background of distant stars, usually appearing to move eastward.

Compared to Earth, the exoplanets that move slower would appear to be stationary and moving westward. Planets don't suddenly stop their motion and go backwards. If planets stopped their orbits there would be serious gravitational consequences. They would fall into the Sun.

The second annotated image shows the path of Mars through the constellation Taurus. As Mars gets closer to the "horns" of Taurus, its daily movement slows so that it appears to be moving in retrograde motion.

On November 30, the Earth will pass between the two "horns" of Taurus, when the Earth will be closest to Mars. Mars' orbit is not a perfect circle. After November 30, Mars will move further and further away from us.

But this is not a Mars opposition. At this time, the Earth is still between Mars and the Sun, and Mars is high in the sky. Its current position is close to the position of the Sun in late spring. When Mars is at its closest approach, the so-called perihelion opposition, Mars will be low in the sky, close to where Saturn is tonight, and no higher than one-third of the distance from the horizon to the dome.

Mars is a reddish-brown sphere in a telescope. If the sky is clear, more features of Mars can be seen.

Take a look at the beginning of Mars' retrograde motion in early December, when Mars appears low in the east-northeast during the evening hours.

Image (October 30, 2022): The movement of Mars compared to distant stars in the constellation Taurus. It can be seen that Mars begins to move retrograde tonight.

Related knowledge

Mars (Latin: Mars; astronomical symbol: ♂), formerly known as Yinghuo, is the fourth planet from the sun and the second smallest planet in the solar system after Mercury. It is one of the four terrestrial planets in the solar system. Mars is called Mars in the West, the god of war in Roman mythology, so in English, Mars means the Roman god of war, and is usually called the "red planet"; in ancient Chinese, it is called Yinghuo because it glows like fire and its position and brightness often change, making it unpredictable.

Mars is the second smallest planet among the eight planets in the solar system, with a mass and volume only slightly larger than Mercury. The diameter of Mars is about half that of the Earth, and its axial inclination and rotation period are comparable to those of the Earth, but its orbital period around the Sun is nearly twice that of the Earth[3]. Mars is visible to the naked eye on Earth, with a brightness of up to -2.91, only dimmer than Venus, the Moon, and the Sun, but dimmer than Jupiter most of the time. Mars is 54 million kilometers away from the Earth at its closest point (the farthest is 400 million kilometers, and it takes about 7 months for a probe to fly to Mars).

Prograde motion is the direction in which a celestial body, such as a planet, moves in concert with other similar bodies in its system; retrograde motion is motion in the opposite direction. In the case of celestial bodies, these motions are either real, defined by a proper rotation or orbit, or visual, as when viewing the sky from Earth.

The English word for "direct" is direct or prograde. The former is a traditional term in astronomy, while the latter first appeared in 1963 in a professional article related to astronomy (J. Geophys. Res. 68, 4979).

BY: Jeffrey L. Hunt

FY：Astronomical volunteer team

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