StarAtlas, Wife and mother-in-law illusion, Why the Moon has more craters than Earth

[Nostromics Newsletter]

Nostromics Newsletter

Nostromics science gifts product news, educational resources & science tidbits

Nostromics Newsletter, 2 February 2011 - You are welcome to share this mail

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StarAtlas

Would you like to know what's up in the sky right now? Visit StarAtlas, a quick and simple online star atlas you can access with a web browser.

When visiting the StarAtlas site, by default it displays a map of the sky you can see at your current time and location, determined from the network connection. Set a different location by entering its name in the text field above the world map and clicking "Set location".

The sky map includes stars, planets and constellation names. Compass points around the edge indicate above which part of the horizon you should look.

The wife and mother-in-law illusion

Our Wife And Mother-in-law Illusion Tote Bag shows a surprising and funny cognitive illusion known as ambiguous illusion. The design features the 1915 drawing "My Wife and My Mother-In-Law" by cartoonist W. E. Hill. In the image you see either a young woman or an old one, but not both. Click the image to get a larger version. These different states of perception are mutually exclusive. We hope you don't see only the old woman.

T-shirts and apparel with the same design, like the Wife And Mother-in-law Women's Organic T-Shirt and long sleeve T-Shirt, are in the Illusions section of Nostromics Store.

More science gifts and products at Nostromics Store.

Why the Moon has more craters than the Earth

The Moon is covered with countless impact craters dug by all sorts of objects that hit it, from tiny dust particles to large asteroids. Both Earth and Moon move in the same region of the Solar System, so our planet should have gotten the same kind of bombardment. Possibly even more, because of the larger Earth gravity. Yet the surface of the Moon has many more impact craters. Why?

Our planet was indeed hit by many objects. But the surface of the Earth undergoes continuous change. Tectonic plates slowly drift, new mountains form, and volcanoes erupt. The atmosphere and water bodies slowly erode the surface. It takes a few tens of millions years to erase an impact crater, or significantly alter its appearance and make it unnoticeable. Over the past 4.5 billion years since the Earth-Moon system formation, however, the Moon kept a lot of its impact scars because it doesn't have enough energy to sustain such geological activity, and has no liquid water or significant atmosphere.

-- Paolo Amoroso & Mauro Arpino (Nostromics), science educators - Milan, Italy

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Copyright (C) 2011 by Paolo Amoroso and Mauro Arpino