... Kepler's 3rd Law . 21a.Applying 3rd Law . ... Besides the Moon, Earth now has many artificial satellites, put up by us earthlings for a variety of purposes. ... where for a satellite orbiting Earth at distance of one Earth radius R E , the constant k equals k=gR E 2 . ... The velocity for a circular Earth orbit at any other distance r is similarly calculated, but one must take into account that the force of gravity is weaker at greater distances, by a factor (R E / r) 2 . ...

One possible application of a solar sail is a spacecraft to warn Earth of approaching interplanetary disturbances and shocks. ... Spacecraft that can provide such a warning are currently stationed at (or near) the Lagrangian L1 point , between the Earth and the Sun--at about 4 times the distance of the moon and 1/100 times that of the Sun. ... Because of the greater distance from Earth, the Earth's pull there is weaker, not enough to make the spacecraft match the Earth's motion around the Sun. ...

... Subject of Astronomy. ... Basis of Spherical and Practical Astronomy. ... Celestial Sphere. ... Changes of Star's Coordinates as a Result of Daily Rotation of Celestial Sphere. ... Time Measuring. ... Changes of Solar Equatorial Coordinates. ... Stellar Day, Stellar Time. ... Real Solar Time. ... Mean Solar Time. ... Connections between Stellar and Mean Time. ... Apparent Path and Configuration of Planets. ... Ways of Energy Transportation to Stellar Surface.Basis of Spectral Analysis. ... Solar...

home publications > mercury . SEARCH ASP SITE: Match ALL words Match ANY word . Books . ASP Conference Series . Monograph Publications . IAU Publications . Books of Note . ... Publications of the ASP (PASP) . ... Mercury Magazine . ... VOLVELLES! Early Paper Astronomical Computers . ... People always have been fascinated by the movement of objects in the sky. ... Thus, events in the sky were important for the day-to-day life of many early civilizations. ... publications . ...

... Tonight's Sky . ... PHASE т?? ... Supernova showered Earth with radioactive debris . ... Astronomy for Kids . ... Swift satellite records early phase of gamma-ray burst . ... United Kingdom astronomers, using a telescope aboard the NASA Swift satellite, have captured information from the early stages of a gamma-ray burst - the most violent and luminous explosions occurring in the universe since the Big Bang. ... Only registered members of Astronomy.com are allowed to comment on this article. ...

Phoebe . Saturn IX . Phoebe [FEE-bee] is the last of the known satellites of Saturn, at a distance of 12.952 million kilometers (8 million miles). Phoebe orbits Saturn in a retrograde direction (opposite to the direction of the other satellites' orbits) in a plane much closer to the ecliptic than to Saturn's equatorial plane. ... Scientists believe that Phoebe may be a captured asteroid with a composition unmodified since the time it was formed in the outer Solar System . ...

Astronomy Picture of the Day . ... 14.06.1997 . ... Credit: F. Summers ( Princeton ), D. Cox, R. Patterson, E. Wesselak, and B. Sanders ( NCSA ), L. Carpenter ( Pixar ), GC3 , Cosmic Voyage , Smithsonian Explanation: What did our universe look like when it was young? ... Galaxies and long filaments formed - which are shown by the bright patches and streaks in the above frame . ... June 1997 . ... Building Galaxies in the Early Universe . ... Unexpected Galaxy String in the Early Universe . ...