Quote:
Originally Posted by malp
These are beautifully resolved images, tremendous colour.
|
Thanks Malcolm for your most generous remarks.
Quote:
Originally Posted by coco1
At the risk of sounding like a fool, my question is, why does mars not look round. It seems to have a flat side. I thought it was just my shots that looked not perfectly round.
Thanks Steve....
|
Hi Steve, hey I am an ex mine worker that managed to do a Grad Cert Sc in Astronomy and I asked heaps of silly questions. I say to you what my unit instructors said to me, "There is no such thing as a silly question".
Steve, the further each planet is from the Sun the slower is its orbital velocity. Earth is orbiting faster than Mars. Before Christmas we were catching up to Mars and at opposition Mars was physically opposite the Earth, relative to the Sun. At that time, from our perspective the Sun fully illuminated the disk of Mars and it looked round. We are now moving away from Mars so we see one limb of Mars sharply illuminated but part of the opposite limb is now in shadow, so it now appears as more of an ellipsoid shape, this was also the case prior to opposition when we were catching up with it. Mars, tonight is exhibiting a phase of 94.88% and it is the part that is now in shadow that creates the effect that you see in current images of Mars. If you go back through this forum and look at images from late in January you will see the full disk of Mars illuminated and it will look round.
Hope this helps.