APOD: Mercury on the Horizon (2013 Feb 19)

[Jim Herbert]

Joe, thanks again for this:

"Direct (eastward) and retrograde (westward) motion are defined by the planet's movement relative to the background stars, not to be confused with the retrograde loops of the exterior planets." There were some assumptions in my ideas that this has corrected.

[Boomer12k]

Or, if you have a computerized telescope you can get a shot of Mercury even through the branches of the trees at the end of the street! If you're LUCKY!

Shot was early morning, just before sunrise. Actually this one was above the trees, barely. This was the SECOND time I had ever SEEN MERCURY, both were with my 10" Meade. A bright, fiery red dot. Even knowing where it was, I could not find it with my 10 power binoculars. Very difficult even with computer controls, as it is not totally centered when the scope finds it. So, you have to hunt a little bit. But worth the wait...

Click on the picture, then click again for close up, and you can see the PHASE. Picture should actually be flipped horizontally for proper view, the sun was low to the left. It was early August 2012. My focus also isn't very good, and the atmosphere interferes too.

The picture looks dark, but the sky was actually early dawn.

:---[===] *

Boomer, you're probably going to have better luck finding Mercury with a computerized scope during dawn apparitions than evening apparitions. My go-to scope needs two bright stars for alignment before it can find planets. In the evening Mercury will be setting and low toward the horizon by the time the stars come out, whereas in the morning if you get up before dawn you can align your scope and wait for Mercury to rise.

As Joe and Chris said, I find it pretty easy to see Mercury with binoculars and naked-eye during decent apparitions (although unlike Joe I don't even try to see poor apparitions). The most important thing is to find someplace with an unobstructed horizon -- my local hilltop park works well. And you need to look at the right time. For evening apparitions get out around sunset and start scanning, you'll see Mercury within 30 minutes. In the morning start looking around Mercury's predicted rising time, and again you should be able to see Mercury within 30 minutes or so. In either the morning or the evening you'll get the best view when Mercury is highest in the sky: as soon as possible in the evening, and as late as possible in the morning.

Given the amount of atmospheric distortion during Mercury's low appearances, I find I get a steadier view through a smaller aperture telescope. In my 70 mm refractor at 50x magnification, when the atmosphere is relatively steady I can see Mercury's phase.

--------------------------------------------------------------------------------------
SIR!!!!
Thank you for your input and suggestions. Much Appreciated. I value your expert advise, and admire your work!!!!
I do not have the luxury of an unobstructed view. Even up on the hill, we have a park with tall trees. No way viewing of ANYTHING, but straight up is happening. On my street in the Summer, leaves block most everything. I was lucky to see it at all. Only because it reached just over the top of the trees. Dawn was really already happening. I could well see everything around me. Software is little help, in that it does not show my particular tree line. So, even knowing the positions relative to other stars or planets is of little help. Could not see other stars for reference. I have bad eyesight to begin with, and against the dawn could not see it. Even with my scope ON IT, could not find it with my Binocs. The other time I saw Mercury was just through the branches in Winter, so no leaves. Man what a sight. Whitish-fiery red, it was AWESOME, I was "struck". Wish I had, had my camera back then.
So, it maybe overly stated to be difficult...if you have the unobstructed view, and are relatively experienced with Mercury. Which I don't have, and which I was not. So, in my particular case, "nearly impossible without a computerized scope", is quite accurate. From my situation.
Here is a photo of the east end of our street, from my driveway, where I do my Astronomy. Poor as it is. The red dot is where Mercury was in my shot, maybe a tad lower. (May not be exact. But you get the idea.) And the dot is over-sized for emphasis. The Yellow dot is where I saw it the first time through my scope. There may have been an evening time, I forgot about in the West, but it was like the yellow dot, just barely, through some branches, in Winter. I have a RELATIVELY unobstructed view to the SE, SW, NW, NE, and E above the treeline. I have a HUGE Oak tree that blocks the North almost entirely, across the street, I can just see Polaris. The south is blocked by the house and trees somewhat, the west is like the east, with a higher treeline. So, I hope you can appreciate my predicament. I PRAY for a HUGE WIND STORM to take down that Oak Tree!!!!!!! Or make it a law that the horizon MUST BE CLEARED!!!! But until then, you can see what I deal with. Lucky to see anything. M16 is South, I can get it just before it goes into the trees!!!
I also do not have the luxury of taking my 100 pound scope and dolly in my 240 Z, out to a deserted location. Not happening. So, you can see I don't live at the top of Mauna Kea, and Mt. Palomar was taken.

I am thinking of going back to a smaller computerized refractor....hmmmm...got some tax money coming back soon....hmmmmmmm....

I had a friend bring back my old Jason, I gave him, the camera would not fit the eyepiece holder.

Clear Skies, and unobstructed views, everyone!!! Space telescopes are the BEST!!!!

:---[===] *

[Anthony Barreiro]

... .
Here is a photo of the east end of our street, from my driveway, where I do my Astronomy. Poor as it is. The red dot is where Mercury was in my shot, maybe a tad lower. (May not be exact. But you get the idea.) And the dot is over-sized for emphasis. The Yellow dot is where I saw it the first time through my scope. ... .

I also do not have the luxury of taking my 100 pound scope and dolly in my 240 Z, out to a deserted location. Not happening. So, you can see I don't live at the top of Mauna Kea, and Mt. Palomar was taken.

...

Clear Skies, and unobstructed views, everyone!!! Space telescopes are the BEST!!!!

:---[===] *

We all do what we can with our equipment, location, and sky conditions. I would much rather see what I can from my light-polluted back yard with its ridiculously obstructed horizon than sit around inside complaining that you can't see anything in the city. Trips to dark sky locations are a real treat.

[DavidM]

Do the nightly positions of Mercury take into account the gradual westward movement of the Sun at sunset? In other words, are we seeing positions of Mercury relative to the mountain backdrop, or relative to the setting sun?

[Chris Peterson]

Do the nightly positions of Mercury take into account the gradual westward movement of the Sun at sunset? In other words, are we seeing positions of Mercury relative to the mountain backdrop, or relative to the setting sun?

I'd say, to a first approximation, the vertical movement is relative to the Sun, but the horizontal is relative to the horizon. The time of each shot seems to have been determined by fixing the distance of the Sun below the horizon, so the image reflects the drift in sunset position over the time series.

[alter-ego]

Do the nightly positions of Mercury take into account the gradual westward movement of the Sun at sunset? In other words, are we seeing positions of Mercury relative to the mountain backdrop, or relative to the setting sun?

I'd say, to a first approximation, the vertical movement is relative to the Sun, but the horizontal is relative to the horizon. The time of each shot seems to have been determined by fixing the distance of the Sun below the horizon, so the image reflects the drift in sunset position over the time series.

I've created two composites simulating the Mercury composite today. The location is Spain, and date range is Feb 1 to Feb 25, 2000. The green region is a fake semitransparent ground (W = West in the base image). The base image is for a fixed horizon, and you can see the motion of the Sun along a line 10° below the horizon. The hover image is the same date range, but the sun is fixed, also at 10°below the horizon (i.e. horizon moves). I've left off the "W" in this image. You can see that the bulk of Mercury's motion along the horizon is do to the Sun's relative motion. The hover image does show that a little less than half of the planet's motion along the horizon is relative to the Sun. I believe this is a reasonable representation.

Click to view full size image 1 or image 2

[MargaritaMc]

BRILLIANT! Thanks so much, alter-ego. It clarifies things for me as well.
Margarita

[Anthony Barreiro]

I've created two composites simulating the Mercury composite today. The location is Spain, and date range is Feb 1 to Feb 25, 2000. The green region is a fake semitransparent ground (W = West in the base image). The base image is for a fixed horizon, and you can see the motion of the Sun along a line 10° below the horizon. The hover image is the same date range, but the sun is fixed, also at 10°below the horizon (i.e. horizon moves). I've left off the "W" in this image. You can see that the bulk of Mercury's motion along the horizon is do to the Sun's relative motion. The hover image does show that a little less than half of the planet's motion along the horizon is relative to the Sun. I believe this is a reasonable representation.

That is really helpful. I've been looking at this beautiful apod repeatedly since yesterday, and I'm seeing the motion of Mercury passing between the Earth and Sun. You can't see this movement at a point in time, and even building up a mental picture through repeated observations is much less vivid and immediate than this image. Thanks imagers!

[alter-ego]

That is really helpful. I've been looking at this beautiful apod repeatedly since yesterday, and I'm seeing the motion of Mercury passing between the Earth and Sun. You can't see this movement at a point in time, and even building up a mental picture through repeated observations is much less vivid and immediate than this image. Thanks imagers!

I thought I'd take this one step farther. The pictures in my original post were modified to include a snapshot of of Mercury's orbit (red elipse) on Feb 14. It's clear the deviation from this orbit is due to Earth's movement over 25 days and the changing perspective of Mercury's tilted orbit wrt Earth's orbital plane. So I've further separated out the Earth / Mercury relative motions in the GIF below. Our evolving perspective of Mercury's orbit (wrt the Sun) is visible as well as Mercury's position. I think you might like this.

 

Click to view full size image 1 or image 2

[MargaritaMc]

Gosh. That is SO skilful, alter-ego. And SO helpful.

[alter-ego]

Gosh. That is SO skilful, alter-ego. And SO helpful.

Thank you very much, MargritaMc, I'm happy you and others found these graphics helpful. I really enjoy and appreciate having the APOD platform to share these things.