Science Porn

[vorlon13]

Here's a good GIF:

https://www.nasa.gov/sites/default/files...star-2.gif


What you are seeing there is from a portable telescope set up in Argentina 7/17/17 showing New Horizons target Kuiper Belt Object MU69, 4,100,000,000 miles away passing DIRECTLY between the prepositioned telescope and a very distant background star.

Each frame of the GIF (sorry, don't know how many there are in the GIF total) represents 200 milliseconds.  By the length of time the star is obscured, astronomers can deduce how large it is and that information will help plan New Horizons encounter with that distant rock.

Additionally, MU69 is still so far from New Horizons that it's best camera does not register it yet.

By having an accurate size and positional information, the New Horizons probe can accurately point it's cameras and sensors during the flyby for maximum science value. 

Additionally, if there are secondary blinks or dimmings of the background star, it would be indicative of MU69 either being a binary object, or having rings and/or satellite(s).

Also, if the dimming of the starlight is 'stepped', that is falls to a certain value, holds steady, then goes out, and then comes back at a reduced but steady amount for a bit before returning to full brightness, it is indicative of the distant star being a close binary.