Night Sky Photography -- 10-06-2020 -- Mars At Its Closest Approach To Earth

Good morning, fellow stargazers!

Earlier this morning, I took this photo of bright Mars moving slowly towards the western horizon. This month, Mars appears as the 4th brightest celestial body in the night sky after Venus because today, October 6 of this year, Earth and Mars are now closer together than they will be again for another 15 years.

 

At present Mars is only about 38.5 million miles from us -- that's actually close in terms of distance in space. Mars is only a week away (October 13th) from its opposition to Earth, or with Earth directly between Mars and the Sun. This happens once roughly every two years.

 

Because it is the forth planet in our solar system, Mars' orbit around the Sun takes 687 days in contrast to our own 365 days here on Earth, giving Mars a year that's nearly twice as long as ours.

 

Okay, I know what y'all are asking: why is Mars closer to Earth today and not a week from now when in opposition? The reason for this has to do with the the paths of the planet's orbits around the Sun.

 

Planetary orbits are not perfectly symmetrical circles around the Sun. All planets have elliptical, or oval shaped, orbits. Because of this planetary orbits have both an perihelion (closest point) and aphelion (farthest point) from the Sun. The planets also move in slightly different angles relative to each other based on both the gravity of the Sun, and on each other slightly.

 

Because the other planets pull on Earth -- and Earth on them -- the planet's orbits change slightly over time, in orientation and in shape. The biggest effect is that the orbit of a planet gradually shifts its orientation slowly over time.

 

Because of this moments of closest approach are fleeting as both Earth and Mars move in their orbits around the sun. Previous oppositions between the two planets have been closer -- the closest being the opposition with Mars in 2003 when the Red Planet was at 34.6 million miles distance, its closest approach to Earth in about 60,000 years (or 30,000 years for Mars)! Because of the orbits between our two worlds, subsequent approaches and oppositions will be slightly farther away for the next two centuries.

 

Also on the night of opposition (October 13th), Mars will actually appear at its brightest in the night sky from our perspective here on Earth. This is due to a neat little phenomenon called the Opposition surge. Already Mars currently outshines Jupiter, the largest planet in the solar system, and will for the rest of this year. 

Be sure to check out this year's opposition of Mars on the 13th as there will not be another one until Thursday, December 8, 2022, with the closest approach to Earth a week earlier on December 1st. 

Until next time have a wonderful Dixie day, and be sure to keep your eyes to the evening skies, y'all.