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  Let the average orbital radius of a planet be R. Let the orbital period be T. What quantity is constant for all planets orbiting the Sun?

  Posted by jayy000 on Dec 12, 2009 at 08:27 AM

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  Satellite A has twice the mass of satellite B, and rotates in the same orbit. Compare the two satellite's speeds

  Posted by hrrjack on Dec 12, 2009 at 08:11 AM

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  Mars has a mass of about 6.39 x 10^23 kg, and its moon Phobos has a mass of about 9.8 x 10^15 kg.

  Posted by won on Dec 7, 2009 at 05:15 AM

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  Given: G=6.67259 x 10^-11 N times m^2/kg^2 A satellite moves in a circular orbit around Earth at a speed of 2620 m/s.

  Posted by lala2pretty on Dec 7, 2009 at 04:43 AM

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  When considering only the Sun,Earth,Mercury, and Mars in a planetary system, which statement is correct?

  Posted by juniormax on Dec 7, 2009 at 04:39 AM

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  Why is this December (2009) a Blue Moon month?  How often is there a Blue Moon Eclipse?

  Posted by enotechris on Dec 4, 2009 at 07:49 PM

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  What's the Dark Rift in the Milky Way?  What does it have to do with the world ending in 2012?

  Posted by enotechris on Dec 4, 2009 at 11:31 AM

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  A switch and light next to each other are connected by a wire going around the Earth. How long until the light lights when the switch is pressed?  

  Posted by enotechris on Nov 28, 2009 at 11:28 PM

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  During a solar eclipse,the moon(of mass 7.36x10^22kg), Earth(of mass 5.98x10^24kg), and Sun(of mass 1.99x10^24) lie on the same line,

  Posted by lala25 on Nov 24, 2009 at 05:41 AM

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  Satellite moves in a circular orbit around the Earth at a speed of 5.1 km/s.

  Posted by jayjay00 on Nov 24, 2009 at 05:17 AM

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  Given: G=6.67259 x 10^-11 N m^2/kg^2 Mimas, a moon of Saturn, has an orbital radius of 1.88 x 10^8 m and an orbital period of about 23.48 h.

  Posted by hrrjack on Nov 23, 2009 at 04:54 AM

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  What did Newton discover about gravity?

  Posted by lala25 on Nov 23, 2009 at 04:49 AM

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  What is the orbital velocity of the asteroid? Assume there are 365 days in one year. Answer in units of m/s.

  Posted by shawn123 on Nov 23, 2009 at 04:46 AM

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  What is the period of the asteroid's orbit? Answer in units of year.

  Posted by jayjay00 on Nov 23, 2009 at 04:44 AM

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  Who invented the astonomy calendars?  

  Posted by reece3 on Nov 19, 2009 at 06:59 AM

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  What is the mass of the Earth using Newton's and Kepler's Laws? What are the step to solving the equation?

  Posted by mjgaudio on Nov 15, 2009 at 11:30 AM

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  Is there life on Mars? Has there ever been life on Mars? Could we possibly live on Mars someday?

  Posted by xtreme69 on Nov 14, 2009 at 03:01 PM

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  When you look up at the sky, why do you sometimes have to look at a star to see another one that is next to it?

  Posted by raudelmendoza on Nov 4, 2009 at 03:46 PM

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  Two stars are observed in the sky.

  Posted by natersuk on Oct 23, 2009 at 08:35 AM

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  Who invented the first calendar? Why do we have a leap year?

  Posted by mee123 on Oct 21, 2009 at 06:08 PM

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  Can I have details of the moon?

  Posted by vaugn on Oct 15, 2009 at 01:56 AM

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  Where is Halley's Comet currently? How do you know?

  Posted by kelly1391 on Jun 11, 2009 at 05:52 PM

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  Is there gravity in space?

  Posted by rukiazanab on Jun 10, 2009 at 11:26 AM

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  Do aliens exist?

  Posted by chachame on Jun 4, 2009 at 06:33 AM

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  Why does the Earth move from west to east?

  Posted by sizan on May 9, 2009 at 10:07 AM

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  How does a spectroscope enable astronomers to determine the characteristics of distant stars and galaxies?

  Posted by fawzia on May 1, 2009 at 10:06 AM

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  How can the universe be never-ending, yet can be classified as an oval? Also, how can it be never-ending, and if it does end what's beyond the ends?

  Posted by aaaaaaaa on Mar 30, 2009 at 06:36 PM

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  Can there be such a thing as a black hole cluster, with multiple  black holes in very very small distances?

  Posted by aaaaaaaa on Mar 26, 2009 at 05:47 PM

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  how does the earth stay in the orbit?

  Posted by danceangel on Feb 28, 2009 at 03:17 AM

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  How many moons does Saturn have?

  Posted by kharizza on Feb 24, 2009 at 08:15 PM

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  What is the size of the sun's atmosphere?

  Posted by sheysel on Feb 24, 2009 at 06:32 PM

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  How do stars form?

  Posted by angelsfall-likestars on Feb 21, 2009 at 04:26 PM

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  how do we stay still when the earth is moving

  Posted by danceangel on Feb 20, 2009 at 03:29 AM

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  What is a prostar?

  Posted by sunnie on Feb 4, 2009 at 05:08 PM

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  Why is the solar system called a system?

  Posted by kennwin on Feb 3, 2009 at 05:26 PM

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  Explain why the Moon exerts a greater tidal influence on the Earth than the Sun.

  Posted by taytay530 on Feb 1, 2009 at 11:19 AM

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  Why do we live on earth?

  Posted by clisty on Jan 26, 2009 at 11:54 AM

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  Is there extra terrestrial life in outer space?

  Posted by hgjhgj on Jan 13, 2009 at 06:04 AM

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  What is the Southern Ring of Nebula and what is it made of?

  Posted by ethan3 on Jan 8, 2009 at 03:18 PM

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  What is the color of the sun?

  Posted by cookey on Jan 5, 2009 at 01:41 PM

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  What is a Galactic Year?

  Posted by enotechris on Dec 28, 2008 at 05:17 PM

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  What really was the "Star" of Bethlehem? 

  Posted by enotechris on Dec 25, 2008 at 09:08 AM

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  Please furnish me with model calculations height of the midday sun in any time of the year.

  Posted by najmsalahi on Dec 20, 2008 at 03:25 PM

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  Please, enlighten me on how to mathematically derive accurate moon phases, i.e. mathematical derivative for moon phases. Thank you.

  Posted by najmsalahi on Dec 18, 2008 at 12:33 PM

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  Describe the sun's atmosphere.

  Posted by shatiria94 on Dec 17, 2008 at 09:32 AM

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  Is there gravity in outer space? Explain.

  Posted by lee00010 on Dec 13, 2008 at 06:41 AM

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  Why does Mars have a longer year than Earth?

  Posted by zero0master on Dec 8, 2008 at 02:19 PM

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  What is an expanding universe?

  Posted by leydibug on Nov 29, 2008 at 04:48 PM

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  How many moons does the sun have?

  Posted by punkydoolikeyou on Nov 19, 2008 at 11:08 AM

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  Why and how did Pluto die?

  Posted by lacibabyy00 on Nov 18, 2008 at 09:13 AM