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Dear Dr. Universe: How did people figure out how much a whole planet weighs? They could not have just put it on a scale! How did they do it? – Angel, 14, California

About 300 years ago during another pandemic, there was a person named Sir Isaac Newton who spent a lot of time at home thinking about the universe. He was thinking about how objects fall and started to wonder if the same force that made objects fall also kept the moon in its orbit. He called this force gravity. That’s what I found out from my friend Guy Worthey, an astronomer at Washington State University. Gravity plays a big part in the answer to your question, and we’ll explore that in just a moment. Read More ...

Hello Dr. Universe: I was wondering, how does an eclipse happen? - Susan, 13, San Francisco, CA

Dear Susan,

It just so happens the Great American Eclipse is coming up on Aug. 21, 2017. This solar eclipse will be the only one visible from across the lower 48 states in nearly a hundred years. When it happens, parts of the country will experience darkness for a couple minutes during the day.

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What is the Kuiper Belt? -Zaara A., 7, Deep Bay, Australia 

Dear Zaara,

You might say the Kuiper Belt is the frozen frontier of our solar system. Out beyond Neptune’s chilly orbit, this saucer-shaped region is home to Pluto, billions of comets, and other icy worlds.

“The Kuiper Belt is really the edge of knowledge,” said my friend and astronomy professor Guy Worthey when we met up in the Washington State University planetarium.

“Out there it’s a little dim,” Worthey said. “We are pretty far from the Sun.”

In fact, it’s about 3 billion miles away. Even at the speed of a jet airplane, it would take more than 680 years to travel from Earth … » More …

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Dr. Universe: Are aliens real? -Lily, 10, New York City, NY Is there life on other planets? -Heidi, Cincinnati, OH 

Dear Lily and Heidi,

Well, we don’t know for certain. Looking up to the stars at night, I’ve often wondered if alien cats are out chasing alien mice or taking naps on other planets.

My imagination aside, your questions are like those scientists are asking, too. And it’s no wonder we are so curious.

With billions of planets in our galaxy, including small Earth-like worlds, the possibility of life out there is an exciting thought to many people. So, humans have set out to look for planets that might support life.

In fact, this month scientists announced the Kepler spacecraft’s discovery of … » More …

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