The Moon – Then & Now



The View from Galileo’s Telescope

On November 30, 1609 Galileo started observing and sketching the Moon.  He was probably not the first person to look at the Moon through a telescope, but Galileo had made himself a telescope that was much better than the others, and he could see the Moon’s surface in much more detail. Galileo described the surface of the moon as being uneven and rough and “crowded with depressions and bulges.”  In his sketches, like the one below, he shows clearly that the line between the light and dark sides of the Moon that looks so straight with the unaided eye, is in fact ragged from the long shadows cast by mountain ranges and (as we know now) craters. In fact, the surface of the Moon was pretty much like the surface of the Earth!


Above: One of Galileo’s first sketches of the surface of the Moon. Image Credit: Octavo Corp./Warnock Library)



Before Galileo’s observations the Moon was thought to be a perfect, smooth sphere (the light and dark regions that can easily been seen by eye were unexplained blemishes on a smooth surface).  The perfection of the heavens set the planets apart from the imperfect Earth.  But now the Moon was revealed to have very Earth-like mountains and valleys.  If the Moon, and maybe the other planets, have Earth-like features, could not the Earth be a planet too?




Above: Archive MicroObservatory image of the Moon.  How does the phase compare with the image you obtained?


What did YOU See with MicroObservatory?

How does the Moon appear in your image taken by MicroObservatory? Did you have a chance to step outside and see the Moon with your own eyes last night?  If so, how does your image compare with your memory of how the Moon looked? Is Galileo’s sketch an accurate representation of the actual Moon, or do you think he took “artistic license” to emphasize the major features?


To see your image of the Moon more clearly, you may want to open it in our MicroObservatory image processing software.


The Moon - 400 years later

The Moon is the only place in the Universe, beyond Earth where human beings have set foot.  The Apollo missions in the 1960s and 1970s gave us tremendous insight into the history and structure of the Moon.  The lighter regions of its surface are over 4 billion years old.  The landscape is covered in craters that have been preserved because there is no atmosphere, and therefore no weathering, of the surface.  The darker regions, called Maria (Latin for Sea) because they look like oceans, are actually vast plains of volcanic lava, although the last volcanic eruptions on the Moon ended over three billion years ago.




Above: Do you recognize this? It’s the other side of the Moon! (Image credit: NASA)



When Galileo looked at the Moon through his telescope, his first thought was how Earth-like the features appeared.  The similarity goes beyond anything that Galileo could have conceived. Evidence now shows that the Moon was once part of the Earth, and that an impact between the young Earth and another planet in the early Solar System ripped away a huge amount of the Earth’s outer layers which would later cool and re-solidify as the Moon.



Above: Humans on the Moon.  Can you spot the running astronaut? (Image credit: NASA)


A quarter century after humans last walked on the Moon, NASA is preparing for the next generation of lunar exploration.  In late 2008 NASA will launch the Lunar Reconnaissance Orbiter, with the objectives to finding safe landing sites, locate potential resources and hazards, and test new technologies in preparation for the return of humans to the Moon.



Find Out More


2009 is International Year of Astronomy, chosen to commemorate the 400th anniversary of Galileo’s discoveries with the telescope.  Find out what else is happening by visiting these web sites:


The World site for International Year of Astronomy.


The United States national site for International Year of Astronomy.


NASA’s International Year of Astronomy website.


For more information on the Apollo Mission, go to:


For more information on the Lunar Reconnaissance Orbiter, go to:


Take a look at the full list of objects in MicroObservatory’s Galileo activity, and see how our understanding has evolved over the last four centuries.