... 2015 January 29 . Close Encounter with M44 . ... Explanation: On Monday, January 26, well-tracked asteroid 2004 BL86 made its closest approach, a mere 1.2 million kilometers from our fair planet. ... The remarkably pretty telescopic field of view includes M44, also known as the Beehive or Praesepe star cluster in Cancer. Of course, its close encounter with M44 is only an apparent one, with the cluster nearly along the same line-of-sight to the near-earth asteroid. ... About APOD | ...

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• APOD: 2004 October 2 - Toutatis Nears Planet Earth
• APOD: 2005 October 28 - October Mars
• APOD: August 14, 1995 - Mercury: Closest Planet to the Sun

... Credit Copyright: Carlo Dellarole, Andrea Demarchi Explanation: On Monday, January 26, well-tracked asteroid 2004 BL86 made its closest approach, a mere 1.2 million kilometers from our fair planet. ... The remarkably pretty field of view includes M44, also known as the Beehive or Praesepe star cluster in Cancer. Of course, its close encounter with M44 is only an apparent one, with the cluster nearly along the same line-of-sight to the near-earth asteroid. ... Publications with keywords: asteroid . ...

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• XWare > APOD
• Journal "Peremennye Zvezdy"
• Toutatis Nears Planet Earth

With this knowledge of orbits, we are ready to plan a trip to Mars. ... The spacecraft will already have the 107,000 kilometers per hour (66,500 miles per hour) speed of Earth, whereas Mars moves at only 86,900 kilometers per hour (53,900 miles per hour). ... A speed of about 42,000 kilometers per hour will be enough to escape the Earth's gravity and, when added to the Earth's orbital speed around the Sun, put the spacecraft on a Hohmann transfer orbit to the Red Planet. ... 1,570,000 . ... Earth . ...

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• ASP: A Good Definition of the Word "Planet": Mission Impossible?
• ASP: Science@Saturn: Cassini-Huygens Mission to Saturn and Titan
• ASP: Lord of the Rings

The Moon orbits around the Earth. ... To keep the Moon moving in that circle--rather than wandering off--the Earth must exert a pull on the Moon, and Newton named that pulling force gravity . ... If it was the same force, then a connection would exist between the way objects fell and the motion of the Moon around Earth, that is, its distance and orbital period. ... Newton went further and proposed that gravity was a "universal" force, and that the Sun's gravity was what held planets in their orbits. ...

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• Lagrangian Points
• To the Planets, to the Stars
• Kepler's Second Law

... Bad Astronomy . ... Bitesize Astronomy . ... The Nine Planets . ... The Sun stays at the center and the planets orbit it serenely, each in its place. ... Tiny Pluto, orbiting the Sun an average of nearly 40 times the Earth's orbital radius, has an odd orbit. Most planets orbit the Sun in nearly perfect circles, but Pluto's orbit is noticeably elliptical. ... The orbits of Pluto and Neptune have a coincidental timing to them: Pluto orbits the Sun twice for every three times Neptune does. ...

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• Phil Plait's Bad Astronomy: Bad News:
• Phil Plait's Bad Astronomy: Misconceptions
• Phil Plait's Bad Astronomy: Mad Science

Comets necessarily obey the same physical laws as every other object. ... If one considers only two bodies -- either the Sun and a planet, or the Sun and a comet -- the smaller body appears to follow an elliptical path or orbit about the Sun, which is at one focus of the ellipse. ... Another quantity that is conserved is called angular momentum. ... Comets simply are bodies which in general have more angular momentum per unit mass than do planets and therefore move in more elongated orbits. ...

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• The Planet Jupiter
• Voyager
• Saturn's Moon Phoebe

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . Armagh Observatory, 11 June 2015: Armagh Observatory reports that the next two weeks will provide an interesting opportunity to observe the brightest planet, Venus, and the largest planet, Jupiter, as they move towards one another in the evening twilight. ... The image shows the sky view towards the West at around 11pm on 20 June 2015. ... Professor Mark E. Bailey, Armagh Observatory, College Hill, Armagh BT61 9DG. ...

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• Armagh Astropark: The Planets
• Armagh Astropark
• Armagh Observatory Jupiter Venus Conjunction

... Planets . ... Earth Satellites . ... Looking in the direction of the constellation Cygnus the Swan and launched by NASA in 2009 is the Kepler Space Observatory.Many previous missions searching for exoplanets mainly detected large giant planets, like large hot Jupiters (it is easier to detect larger planets).However KeplerтАЩs main objective is to search for much smaller planets located in a habitable zone which is not too close nor too far from their star; planets which may be just like our Earth. ...

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• The Blue Planet | Astronotes
• How Did New Horizons Get to Pluto So Quickly? | Astronotes

... More on 51 Peg: . The discovery of a Jupiter--mass planet in orbit around the solar--type star 51Peg has been reported by Michel Mayor and Didier Queloz (Geneva Observatory) on October 6th at the 9th Cambridge workshop on "cool stars, stellar systems, and the sun" held at Florence (Italy). ... Recall that the measurements of radial velocity only yield v sin i which in turn gives us M sin i. For most values of i, sin i will be greater than 0.5 and this gives a mass estimate of 0.5 Jupiter masses. ...

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• Moving Towards Life
• Astronomy HyperText Book: Planetary Motion

In ancient times the solar system was thought to be the whole Universe, so the study of planetary motions was cosmology. ... The planets other than the Moon and Sun generally move West to East through the stars, but occasionally stop and move in the opposite direction ( retrograde motion). In order to explain the retrograde motion of the planets, the geocentric model of the Solar System shown above puts the planets on small circles called epicycles . ...

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• Moving objects

. If an object is moving so fast that its kinetic energy exceeds this, it can escape out into space, never to return. Thus . Previous slide . Next slide . Back to first slide . View graphic version .

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• What’s this got to do with velocities?
• Orbits
• University Problem Based Learning Exercises for Teaching Astronomy and Physics

... In a game of ping-pong, suppose a paddle moves at 20 miles per hour and hits a ball with 20 mph in the opposite direction. ... In the new problem, a ball moving at -40 mph hits a non-moving surface; if the collision is elastic (no energy lost), that ball returns with the same speed but in the opposite direction, i.e. its velocity reverses sign. ... Something very similar happens when a spacecraft with velocity v passes close to a moving planet and is deflected. ... Could Earth capture a second moon?...