... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... Risks Comparable to NEOs . ... The Increasing Rate of Discovery of Asteroids . ... Comet and Asteroid Collision Probabilities . ... Extreme albedo comets and the impact hazard (PDF Format) . ... Asteroid Impact Animations . ... Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids - 2002 . ... The Spaceguard Survey Report, 1992 (PDF) . Tsunami from Asteroid/Comet Impacts . ...

Astronomy Picture of the Day . ... Advised by Alexandrian astronomer Sosigenes , Roman dictator Julius Caesar , pictured above in a self-decreed minted coin, created a calender system in 46 BC that contained one leap day every four years. ... This "Julian" calender system was used until the year 1582 when Pope Gregory XIII added that leap days should not occur in years ending in "00" except if divisible by 400, providing a further fine tuning. ... Publications with words: Julius Caesar - Leap Days . ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. February 29, 1996 . Julius Caesar and Leap Days . ... Explanation: Today, February 29th , is a leap day - a relatively rare occurrence. Advised by Alexandrian astronomer Sosigenes , Roman dictator Julius Caesar , pictured above in a self-decreed minted coin, created a calender system in 46 BC that contained one leap day every four years. ...

... Bad Astronomy . Misconceptions . ... Bad Astronomy : The Moon only shows one face to us because it is not rotating. Better astronomy : The Moon only shows one face because it is rotating, once every time it revolves around the Earth. ... Place the Moon model on the table about 30 centimeters (one foot) away with the X facing the Earth model. ... You'll see that to keep the X facing the Earth model, you have to rotate the Moon model as it goes around the Earth model . ... 2008 Phil Plait. ...

... The Round Earth . ... Aristarchus around 270 BC derived the Moon's distance from the duration of a lunar eclipse (Hipparchus later found an independent method). ... Let R be the radius of that circle and T the time it takes the Moon to go around once, about one month. ... Viewed from Earth, a "new Moon" (occuring between the time a thin crescent is last seen before sunrise and the time one is seen shortly after sunset) happens when the Moon in its apparent motion around the sky overtakes the Sun. ...

... Transits do not happen every time Mercury passes between the Earth and Sun because their orbits are not in exactly the same plane, as we will see in this activity. ... Transits of Mercury occur at only two times during the year (but not every year). ... Can you tell which two months the orbits of Earth and Mercury are in line with the Sun? _____________________ and ________________________ [pic] ----------------------- ( Transits of Mercury occur at only two times during the year (but not every year...

... Asteroid . ... In case you didn't hear about it, which you probably didn't: On Jan. 7, an asteroid 1,000 feet across -- nearly three times the current diameter of Marlon Brando -- barely missed the Earth, which is most likely your planet of residence. ... What if this asteroid had hit the Earth? ... As it happens, the American Astronomical Society was holding a conference in Washington AT THE VERY SAME TIME as the asteroid nearly hit the Earth. ...

... Planets . ... Earth Satellites . ... The newly discovered ?mega-Earth? ... Its sibling, the lava world Kepler-10b, is in the background (the two planets? proximity is grossly exaggerated) .€а Kepler-10c has a diameter of about 29 000 km, 2.3 times as large as Earth, and weighs 17 times as much. ... The first mega-earth to be discovered is Kepler-10c which orbits a star lying about 560 light years from the Sun in the constellation Draco. ... Astronomers Find a New Type of Planet: The ?Mega-Earth? ...

... ATNF Home . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . ... Parkes | ... Cosmic engine for senior students . ... The Sun . The Sun is vital for life on Earth. ... The Sun is a typical star, emitting electromagnetic radiation and particles that influence the Earth . ... In the meantime you can view material on the Sun and its influence on Earth written for the first version of the new syllabus here . ...

... Click on this icon if you would like to see a collection of snapshots of actual pages from the "Other Worlds from Earth" Electronic PictureBook. ... The Other Worlds from Earth Electronic PictureBook is a HyperCardЁ stack designed to run on a color MacintoshЁ computer with at least 2.5 megabytes of available RAM, sufficient hard disk space to contain the Electronic Picturebook, System 7.0, and HyperCard 2.1 or HyperCard Player 2.1. ...

... Listed below are questions submitted by users of "The Great Magnet, the Earth" and the answers given to them. ... In "The Exploration of the Earth's magnetosphere" on the magnetic environment of the Earth in space (a few Q duplicated here) . ... 11) Magnetic Shielding . ... 51) Can electricity be generated from the Earth's magnetic field? ... 9) Measuring Earth's magnetic field . ... 6) Reversals of the Earth's field (4 queries) . ... 42) Could generated electricity affect Earth's magnetic field? ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanat