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The moon moves slowly but the Earth rotates quickly. Most of the earth surface can be seen during one day. The earth is not illuminated by sunlight all the time
by exDM69 6y ago
The moon moves slowly but the Earth rotates quickly. Most of the earth surface can be seen during one day. The earth is not illuminated by sunlight all the time, about half of the lunar month would be completely dark.
Moon is in an inclined orbit, which is slightly elliptic. I assume this is what you meant by "ecliptic" (which refers to the orbital plane of the Earth around the Sun). The orbital inclination has the most significant implications to Earth surface visibility, but the Moon is far enough that almost half of Earth surface is visible at all times.
For Earth observation, satellites are better positioned than a lunar surface observatory.
The moon isn't a great place for an outpost or staging point for exploration. Launches and descents are expensive and spoil all the savings. Maybe if LH2/LOX could be manufactured on the moon very cheaply (from water ice), it could make sense to do refueling for exploration vehicles parked on a halo orbit near Lagrange points.
But orbital refueling of cryogenic propellants (especially hydrogen) or manufacturing them on the moon aren't viable in the near future.
There aren't a lot of good economic or exploration incentives to go to the moon, unfortunately. It only has scientific and prestige value. The long lunar night (14 earth days) makes it a poor location for a permanent outpost.
All of that said, I'm all for going to the moon with humans on board.
- saberdancer 6y agoYou are right about Earth rotating. I spaced out on that one. About the ecliptic, I was trying to say that any observatory on the moon would have issues observing polar regions because the Earth surface in polar regions would be at a low angle. I know some spy sats "look ahead" to get better detail resolution but they have ability to look from different angles as well. Moon would be a bad spot for that. Rest of it I mostly agree. One thing up to debate is whether an outpost on the moon would be useful. If you can manufacture fuel on the Moon, it would be very useful. Another aspect is human health in zero G. Moon with low gravity may be enough to help with long term human stay.
- exDM69 6y agoThe lunar orbit is inclined so that the moon moves between about +/- 28 degrees north/south latitude with reference to the Earth equatorial plane. That's Earth's axial tilt of ~23 deg + the inclination of the lunar orbit w.r.t. the ecliptic of ~5 deg. This means that when the moon is at its northest (above southern Florida), it has a pretty good view over the north pole (but it's at quite an oblique angle of ~60 deg), and the south pole is not visible. About 14 days later it's the opposite. But yeah, I agree with the conclusion that the Moon is not a good place for a Earth observation for a lot of reasons.