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Comment by gonvaled | Hacker News Reader

Moon is tidally locked to Earth, which is interesting. How long will this last? How long has this been going on? Does this happen to all satellites in all planets?

Another question: is the Moon orbiting plane aligned with the Earth rotation axis? Why or why not?

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Interestingly, the moon's tidal lock is not perfect, resulting in a wobble that can be seen in time lapses: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4236

I used to work in the SVS and Ernie, who made those images, got to be a real expert on the complexities of the moon's orbit. He did some really great work. Check out the SVS website for more.

You can get the answer to all these questions by reading:

https://en.wikipedia.org/wiki/Tidal_locking

and:

https://en.wikipedia.org/wiki/Orbit_of_the_Moon

The magic of reading!

Reading is the old-school local processing. Asking people is cloud computing, which is hot so it must obviously be better!

HN is becoming a free mechanical turk for reading.

So, the Moon orbiting plane is close to the ecliptic, and the satellite is in the ecliptic (L1 is in the ecliptic). I do not get this:

> About twice a year the camera will capture the moon and Earth together as the orbit of DSCOVR crosses the orbital plane of the moon.

(nitpick: the DSCOVR has no "orbit" around the Earth, since it is in the L1 point)

Since the Moon's orbit and the ecliptic are so close, I would expect this crossing to happen more often (on every turn of the Moon around the Earth)

DSCOVR is orbiting the sun and the earth at the same rate. In one year it will go once around the sun and once around the earth.

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