[X] My Assistant

[paxdan]

they should post in advance the time they are doing this so we can go outside and wave.


what are the chances that MSL will be able to resolve the moon too?

[edstrick]

Io and Europa are about the same diameter as the Moon, Ganymede and Callisto about 30-40% bigger.

But. Earth is 1 AU <by definition, our orbit's semi-major axis> from the Sun. Mars varies 1.3 to 1.5 AU <very roughly> from the Sun and Jupiter is 5 AU from the sun.

So when Earth and Jupiter are on the same side of the sun, the distance is 4 AU, on opposite side, it goes up to 6 AU.

When Earth and Mars are close, it's some 0.3 to 0.5 AU, when they're on opposite sides of the sun, it's 2.3 to 2.5 AU. Always much closer than Jupiter is to Earth.

When Earth and Mars are at 90 degrees from each other, as seen from the sun, , it'll be about 1.3 or so AU.. and the view will be of a Half-Earth and Half-Moon. some 4 times bigger than Jupiters moons in appearance.

[MichaelT]

When Earth and Mars are at 90 degrees from each other, as seen from the sun, , it'll be about 1.3 or so AU.. and the view will be of a Half-Earth and Half-Moon.  some 4 times bigger than Jupiters moons in appearance.

Exactly, and if you waited a little longer, say till Earth has an elongation of 30 deg, as viewed from Mars, it'd get even better. It would be around 1 October 05 when you could see the Moon as a slim crescent of 9 arcsecs diameter, about 5-8 times larger than Jupiter's moons. In an 8" teleskope you could see some craters at the terminator I guess.

And, as a bonus, Venus is located just 2.5 deg from Earth on that day - what a view that would be . I'd recommend the rover team to take a series of images at around 9:50 UTC on 1 October. Using Oppy's pancam you'd get a shot of brilliant Earth (-2 mag) and Venus (-3.4 mag) 12 deg above the horizon at dusk . Oh, if we could just make them do that!

Michael

[ilbasso]

And, as a bonus, Venus is located just 2.5 deg from Earth on that day - what a view that would be . I'd recommend the rover team to take a series of images at around 9:50 UTC on 1 October. Using Oppy's pancam you'd get a shot of brilliant Earth (-2 mag) and Venus (-3.4 mag) 12 deg above the horizon at dusk . Oh, if we could just make them do that!

Michael

Here's a quick and dirty (but artsy) screen shot from Starry Night showing the scene. (Apologies for not cropping out the Windows stuff...I don't have any image editing software on my new machine yet.) That's Venus on the left, Earth on the right, with the Moon just below it. The two planets are nestled in amongst the stars of Libra.

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