Mars Opposition

Specific upcoming events: comets, meteors, supernovae, eclipses, etc.
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Bruce D
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Mars Opposition

Unread post by Bruce D » Mon Jun 04, 2018 7:57 am

It looks like this summer's Mars opposition will be a good one, the best since 2003 which I remember vividly. For those of you new to the astronomy game, in astronomy "opposition" is used in reference to solar system objects that are further from the sun than us (Mars, Jupiter, sometimes the Moon). Opposition is the point in the object's orbit where it is opposite the sun's position from our perspective. A picture being worth more than a thousand words in this case...
Opposition.JPG (14.98 KiB) Viewed 1913 times
NOT Opposition.JPG
NOT Opposition.JPG (15.84 KiB) Viewed 1912 times
The important thing about opposition to us is that when a planet is at opposition it is the closest it can get to us- and yes, in the case of Mars, it will look substantially larger to us. The difference in distance is signifigant, especially for a small planet like Mars. When Mars is way on the other side of the Sun it can be over 200,000,000 miles away (and looks tiny in a telescope)... but when Mars is at opposition it can be as close as 35,000,000 miles away (and YES it will look much larger in our telescopes).

Mars opposition will occur at the end of July this year (it happens every 2 years roughly) and the effect is most pronounced for a few weeks before to a few weeks after so be sure to plan to observe Mars mid-summer and for you imagers time to brush up on your planetary skills!
Bruce D
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Re: Opposed

Unread post by TimW » Mon Jun 04, 2018 11:07 am

It won't make a huge difference given it's size and distance but Saturn will reach opposition on June 27th.
Tim W.

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Re: Opposed

Unread post by AndyG » Tue Jun 05, 2018 12:35 am

Thanks for the diagrams, Bruce. Can't get much clearer than that!

I was reading about how Cassini did the first accurate measurement of the scale of the solar system in 1672 by measuring the parallax of Mars at opposition. He sent his assistant, Richter, to the other end of the earth -- French Guiana -- while he stayed home in Paris. They synchronized their measurements of the position of Mars by using Jupiter's moons as their clock.
Bruce D
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Re: Opposed

Unread post by Bruce D » Tue Jun 05, 2018 6:40 am

Using Jupiter's moons as their clock... very clever those ancients!
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Re: Opposed

Unread post by mrgizmo65 » Tue Jun 05, 2018 6:01 pm

Thank you for illustrating Mars oposition. I find it fascinating that their calculations are in fact not that far off from the calculations with modern instrumentation. With all the obstacles they had they did pretty good. I'm looking forward to observatory Saturn and Mars.Jerry
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