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True Mars color image taken by the OSIRIS instrument on the ESA Rosetta spacecraft during its flyby over the planet in February 2007. Image via ESA.
The red planet Mars is swaying towards perihelion – its closest point to the sun in its orbit – September 16, 2018. The orbit of Mars around the sun lasts 687 Earth days, or about two Earth years. At perihelion, it is 1.38 AU (astronomical units) of the sun. It is 1.38 the Earth-Sun distances.
The perihelion of Mars is an event once every two years. Mars arrived at perihelion on October 29, 2016. His next perihelion will be August 3, 2020.
None of the planets have exactly circular orbits, but most, like the Earth, have orbits around the sun. almost circular. By cons, the orbit of Mars is much more elliptical, more like a circle on which someone sat down and crashed. Its distance to the sun varies between 1.38 AU and 1.67 AU – a variation of more than 20%. From perihelion (closest point) to aphelion (furthest point), Mars receives 31% less heat and sunlight.
A descending image of the orbits of the Earth and Mars. The orbit of the Earth is almost circular. The orbit of Mars is more elliptical; its distance to the sun changes more dramatically. Not on the scale. Image via NASA.
Extra heat and light around the perihelion of Mars are often associated with planetary dust storms on the planet. This has been the case for Mars in recent months. A dust storm erupted in May and went global in June. The dust storm erased the sun, causing the Opportunity rover on Mars to silence; The rover team is still trying to greet him.
Meanwhile, the dust storm began to subside, with the release of dust, for example, on the location of the Curiosity vehicle on Mars. Note the dust on the mobile in the picture below:
Close up of the August 2018 panorama of Mars made by the Curiosity rover. See the dust on the surface of the mobile? Image via NASA / JPL-Caltech / MSSS.
Can you see Mars? Absolutely! In 2018, Earth and Mars are very close to each other because "proximity" is defined for the planets. The Earth passed between Mars and the sun on July 27, and Mars was drawing closer a few days later, on July 30 and 31. Mars was extremely bright in our sky for about a month around these dates. From July 7 to September 7, it was brighter than Jupiter, which is normally the second brightest planet after Venus.
Why was Mars so brilliant this year? The best time to see Mars in the earthly sky is during perihelic opposition. It is at this moment that the Earth oscillates between the sun and Mars – an event called opposition of astronomers – near the time when Mars reaches the perihelion, its nearest point of the sun.
This is what happened in 2018.
Now Mars is still one of the four bright planets of our evening sky. It begins to darken as the Earth flies into orbit. It is not as bright as in July or August, but it is still very bright and well placed to look eastward after sunset to cross the sky for most of the night .
Dennis Chabot of POSNE NightSky in Massachusetts caught this shot of Mars on September 13, 2018. He is still very bright in our sky and distinctly reddish in color.
Watch for the passage of the moon by the planets Saturn and Mars from September 17 to 19. Learn more.
Mars has had its closest opposition (0.37272 AU) since the Stone Age on August 28, 2003. On cycles of 79 and 284 years, Mars has also closed perihelic oppositions. On August 30, 2082, Mars will arrive at 0.37356 AU from the Earth; and on August 29, 2287, Mars and Earth will be separated by 0.37225 AU.
Bottom line: The perihelion of Mars – its closest point to the sun – arrives on September 16, 2018. This is a unique event. More … how you can still see Mars in the night sky.
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