... In 1972 during the Apollo 17 mission, astronaut Harrison Schmitt found out first hand. In this case, the world was Earth's own Moon. Three Planets in Dawn Skies . ... Inner planet Mercury, fresh from its second transit of the 21st century, stands highest in the bright sky at the top right. ... NGC 2174: Emission Nebula in Orion . ... A lesser known sight in the nebula-rich constellation Orion, NGC 2174 can be found with binoculars near the head of the celestial hunter. ... This moon is doomed. ...