# why is there a shadow on the moon

Why is it that during some phases of the moon (1st quarter and 3rd quarter) show a crescent shadow and during mid phase the shadow is a straight line? This is kind of a neat question and it's to do with illuminating spheres and the angles that you look at them with respect to the light source. You could try to an experiment with some help from your friends if you have a ball and a flashlight - it is probably the best way to understand it. One of you has to be the sun (the one with the flashlight) the other the moon (the one with the ball) and the third person is the Earth( you don't get to hold anything! ). If the line between the "Sun" and the "Moon" is at a right angle to the line between the "Moon" and the "Earth" (ie. if the 3 of you stand at 3 corners of a square), half of the "Moon" will be illuminated and the shadow will look like a straight line.

When the Sun moves forward or backwards from this postion more or less of the bit of the Moon that can be seen from the Earth will be lit up and the shadow will now be curved. I hope that explains it OK. Try it out of you can - try to use quite a large ball and do it in a darkened room. I think that it should work OK and it should be fun anyway! It's difficult to work in 3D so playing with models can help! It's a tool many scientists use to understand what's going on. This page was last updated on July 18, 2015.
On June 4, plan once again to get out your lawn chairs, binoculars, and low-power eyepieces. And this year, you better add bug spray. A partial lunar eclipse is on its way. A lunar eclipse occurs when the Moon, in orbit around Earth, passes into Earthвs shadow. Because the Sun isnвt a point of light, the shadow has two parts в the inner, darker umbra and the outer, lighter penumbra.

If the whole Moon enters the umbra, the eclipse is total. If the umbra hides only part of the Moon, the eclipse is partial. Thatвs whatвs happening June 4. Throughout North America, the eclipse begins before dawn. The umbral phase begins at 6:00 a. m. EDT (3:00В a. m. PDT). This is after the Moon sets for the continentвs northeast region, but everyone else can see at least part of the event. For West Coast observers, the Moon will stand more than halfway up in the western sky. Maximum eclipse comes at 4:04 a. m. PDT, when 37 percent of the Full Moon will lie within our planetвs shadow. The eclipse wraps up at 5:07 a. m. PDT. Outside the Americas, the eclipse will be visible across the Pacific Ocean.

Residents of Australia also will see the entire event. And millions of people living in Eastern China will see the Moon rise at sunset already within Earthвs shadow. Try to catch this event because it will be nearly two years until the next easily viewable one. The next total lunar eclipse will be visible primarily over North and South America on April 14/15, 2014. And although another partial lunar eclipse happens April 25, 2013, it occurs during daytime in the Americas. Furthermore, only 1 percent of the Moonвs surface will lie within Earthвs umbra on that date. During the June 4 eclipse, look about 6В to the southwest of the Moon for Antares, the brightest star in the constellation Scorpius the Scorpion. Binoculars may help if dawn begins to light your sky. The field of view of 7x50 binoculars is 7В.

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