During October 2020, Mars appears as a very bright star in the eastern evening sky and western morning sky. Mars is closest to Earth on October 6, and at opposition a week later. This is the closest distance to Mars until 2035. The moon passes the planet twice, October 2 and October 29.
by Jeffrey L. Hunt
This month the Red Planet is at its closest to Earth and at opposition with the sun. Mars the overly bright star that appears in the eastern sky during the early evening hours and is visible nearly all night. As sunrise approaches look for it in the western sky.
Mars and Earth are closest until Earth passes Mars during mid-September 2035.
Mars is the second brightest “star” following Venus. The Red Planet’s brightness varies greatly depending on its distance from Earth.
The moon is visible with Mars on the evening of October 2 and morning of October 3. They appear together again on the evening of October 29, two days before the Halloween Full Moon.
During the month, Mars appears to be moving westward compared to the stars as it nears its closest approach to Earth and its opposition with the sun. The westward motion is an illusion from our faster moving Earth passing Mars.
The chart above shows the motion of Mars compared to the dim starfield of Pisces.
Mars’ orbit is elliptical. This non-circular path takes Mars close to the sun and farther away. The closest point of Mars to the sun (and any other planet) is known as perihelion; its farthest point from the sun is aphelion.
Mars Slideshow for October 2020.
The perihelion distance from the sun is about 20% closer than the aphelion distance.
Mars revolves around the sun in nearly 687 earth days or 1.88 earth years. Earth catches, passes, and moves away from Mars every 780 days (on average) – about 26 months. Sometimes, Mars is near opposition when it is near perihelion. The same occurs when it is at aphelion.
A perihelic opposition occurred July 27, 2018. Earth was closest to Mars four days later. Mars was still moving closer to the sun and had not yet passed its perihelion.
This year, the Martian perihelion occurred August 2. As Earth approaches Mars, Mars is slowly moving away from the sun. The closest distance occurs on October 6.
A week later, Mars is opposite the sun in the sky. Mars rises in the east as the sun sets in the west, appears in the southern sky near midnight, and sets in the west in the morning as the sun rises in the east.
When larger telescopes were developed, observations near oppositions, especially perihelic oppositions, revealed the Martian moons and features on its surface. Other observations led to misconceptions of Martian canals, cities, and life – and perhaps helped promote science fiction stories of journeys to and from the Red Planet.
For those with telescopes or who want more information about Mars see:
- For the latest news in observable Martian features and observing conditions, see the Association of Lunar and Planetary Observers (ALPO) website, http://www.alpo-astronomy.org/marsblog/.
- Another source from ALPO describes large-scale events of the planet’s apparition, http://www.alpo-astronomy.org/marsblog/wp-content/uploads/2020/02/CalendarOfEventsCORRECTED.pdf
- From Sky and Telescope: To determine what is visible on the Martian surface on any date and time, https://is.gd/marsprofiler.
Read more about the planets during October.
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