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Mars??


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Hi all

A couple of times recently I've got up early to find Mars and tick it off my list but if I have found it " and I'm pretty certain" it's rather disappointing just a tiny orange dot and that's in my 10" newt.

I'd read all about being able to see the ice at the poles, am I expecting too much??

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This is the most straightforward definition I have found:

Opposition

The position of a planet when it is exactly opposite the Sun in the sky as seen from Earth. A planet at opposition is at its closest approach to the Earth and is best suitable for observing.

With regards to the apparent size of Mars, it will get larger as it approaches opposition but this time won't get any larger than 13.9 arc seconds. Compare that to Jupiters current 48(ish) arc seconds and you see that Mars will be small in the eyepiece.

With patience and good observing conditions surface details such as pole caps and the darker markings will be visible. Just not very large !

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Mars requires relatively high magnification, steady seeing and lots of patience. A red filter can help for contrast too. It took me several years to get the knack of catching all but the vaguest of details.

It is really small right now. Check back in January when the disc is starting to grow in size :D

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This is the most straightforward definition I have found:

Opposition

The position of a planet when it is exactly opposite the Sun in the sky as seen from Earth. A planet at opposition is at its closest approach to the Earth and is best suitable for observing.

so this is probably a silly question, but when the Moon's in opposition the Earth's shadow covers it so does the Earth cast any shadow on Mars in the same situation?

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For a shadow, they would need to be on the same plane as an example, The Sun, Earth and Mars would need to be on the ecliptic and Mars orbits on an inclination of 1.8° I believe?

A similar scenario would be the moon when it is at opposition. It's similar to say when the moon is full which happens once a month, but we don't get a lunar eclipse each time the moon is full or at opposition and that's because the moon orbits on an inclination to the ecliptic which doesn't put it directly behind the Earth with respect to the Sun.

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so this is probably a silly question, but when the Moon's in opposition the Earth's shadow covers it so does the Earth cast any shadow on Mars in the same situation?
The umbra of the Earth's shadow is a cone, since the Sun is larger than the Earth. Mars never gets anywhere near it.

Mars could pass through Earth's antumbra, which geometrically extends forever. From Mars, this would simply be a transit of Earth across the Sun.

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This animation illustrates it nicely Mars's Orbit

Excellent stuff. Should come in very handy in the future. I now understand why Mars never appears as anything other then a tiny dot with a lighter bit where the caps are to me. I've been trying to observe it at all the wrong times of its orbit.

*EDIT* silly me....i forgot to bookmark it. All done now.

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I was in Tunisia in Sept 2003 when Mars was at its closest to Earth in however long. I was actually on a 2 day trip from my hotel to the fringes of the Sahara at the time (a town called Douz). Mars was spectacurlarly big and bright to the naked eye (on par with Jupiter on its recent opposition). There was almost zero light pollution. The only LP there was the lights of the hotel i was staying in. So i wandered off into the dark for a couple of mins and sat in the Saharan sand.

Its the only time in my life that i have also seen the MW with naked eyes.

I just wish i had my little 70mm travel scope back then.

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I observed Mars through a telescope for the first time in October 2009 all I could see was a tiny orange dot I wasn't even sure it was Mars, but by Jan and Feb 2010 Earth had moved a lot nearer and things were looking up. The views through my 10" Dob were excellent (though still small at the eyepiece) and our next pass early next year will be at a similar distance so weather depending I'm hoping for the same again. After a number of nights I could easily pick out many surface features at x200. The last episode of the Sky at Night had some good information on Mars and is currently on the iplayer.

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Because of the orbits of earth and mars, the distance between the two can vary between about 55 million km to just over 400 million km, and it's size can vary from 3.5 arc seconds to just over 25 arc seconds. It makes a huge difference when you observe mars at opposition

Stu

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The usual "mistake" when observing Mars is to not use enough magnification. We get used to Jupiter and Saturn often running out of steam at much over 200x but Mars does stand magnification better and provided that the scope, the atmosphere and the elevation are suitable, 400x is often better than 200x. Mars is small yet bright, too low a magnification and the detail gets swamped in the glare. One of the attractions of observing Mars is the challenge it presents.

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I'm gonna throw all i have at Mars when it rises at a sociable hour.

130mm scope (f5),4-6mm ep and a 2x barlow. I'll add a 450d camera into the mix just to get the best i can.

This is my best Mars to date:Taken with a 7 mega pixel casio compact on a fixed tripod with 10X digital zoom.

I was chuffed with it.

post-18019-133877692833_thumb.jpg

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