See if you can find Mercury in this movie
by tom

1) Goto the URL: https://sohodata.nascom.nasa.gov/cgi-bin/data_query

2) Click on [Lasco C3]
3) Change the Resolution block to 1024
4) Click on "Movie"
5) Enter [2016-12-27] in "Start and End Dates" block
6) Click on [Search]

Wait for a bit for the images to load

Now see if you cab find the Planet Mercury moving across the image.

Hint #1
There is a lot of "noise" or quick flashes of light going across the frame.
This will make the movement of Mercury show up better:

Scroll down to the bottom of the screen and click on [Faster] 4 or 5 times.

Hint #2 ... Mercury is moving left-to-right above the Sun.

Hint #3 It is faint

Now if you increase the number of images by entering Enter [2016-12-26] in
the "Start and End Dates" block then you'll see Mercury go from bright to dim
as it passes between the Sun and the Earth.

That is .. Mercury is dimest when it passes between the Earth
and the Sun. Why?
 

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If you check SOHO each day,  then the following procedure may be faster:

1) Goto the URL: https://sohodata.nascom.nasa.gov/cgi-bin/data_query

2) Click on [Lasco C3]
3) Change the Resolution block to 1024
4) Click on "Movie"
5) Enter [111] in "latest n images block

6) Click on [search]

Wait for a bit for the images to load .. Then press [Faster] 4 or 5 times

This procedure will load the previous 111 image or about a day's images

From time to time you may see passing star constellations, nebulas, a comet
fall into the Sun, or the apparence of planets passing the Sun.

Suggestion: If you already have planetarium software .. you can use this
tool to identify objects that pass across the SOHO movie frame.  If not then
I recommend downloading and using "StarCalc" for this purpose.

http://homes.relex.ru/~zalex/files_eng.htm

Note:
You only need to load the basic package  "sc573en.zip" and the ecliptic line "eclline.zip"