This week, Mercury peeks out from hiding by the Sun for its evening/eastern elongation - the furthest it will appear in the sky away from the Sun after sunset. This makes it the easiest time to see Mercury in the evening sky. It will still be low on the horizon for most people. I got my first sighting of Mercury in a good while last night. 15 minutes after sunset it was barely above the trees. If you've got a decently clear horizon, you've got a chance of seeing it too. This will not be the only or best opportunity to see Mercury this year; July 3 has a better evening elongation.
Mercury is one of the brightest objects in the sky and visible without a telescope. Currently, its apparent size is well more than half of Mars's apparent diameter right now. So while it's still very small in a telescope, its phase can be seen easily. The conventional wisdom says you can see no features on Mercury with a telescope. But where's the fun in that? Old time visual astronomers attempted several maps of Mercury with their large professional grade telescopes, with questionable results.
So my question for the group is: has anybody been able to spot albedo features or differences on Mercury before? I have seen CN members report albedo features with Ganymede, so it seems within reach. On the other hand, the maps made by past astronomers had almost no correspondence to the photos taken by space probes...
I have a 6" SC. I have managed to obtain images of Mercury with the astronomical camera, with albedo spots from some craters. Last time a few days ago, if you want to see in the planetary imaging section.
Visually through the eyepiece, although I have tried several times, I have not yet been able to notice any surface detail!
At most, a clear gibbous or sickle-shaped silhouette, but always with a uniform white color (in broad daylight, with the planet even 50° above the horizon). The best observations are always between 250x and 333x with a yellow filter or variable polarizer. At 166x the planet was nice and sharp and still, but really too small to notice anything!
I assume that, to be able to notice some minimal detail of its surface, a really excellent seeing is needed (assuming optimal collimation, focusing and acclimatization of the instrument) and in any case not less than 250x and in broad daylight with the planet high in the sky.
The 6 inches of my obstructed telescope are also not the best for contrast... where instead refracting telescopes excel! Surely, with a 6-inch refractor it would be easier, or obviously with a mirror of at least 8 inches.
Anyway, I will continue to try, it is now a personal challenge!
Ps: It would be interesting to have testimonies of those who have managed to observe surface details of Mercury at the eyepiece, perhaps using better setups.
Edited by antarex, 09 March 2025 - 02:45 AM.
