Question | Answer |
Heinrich Olbers | found a second minor planet in the gap and called it Pallas |
Giuseppe Piazzi | found minor planet in 1801 and called it Ceres |
minor planets | are the same thing as asteroids |
Karl Hencke | also found a minor planet,in 1845 and named it Astrea |
asteriods | minor planets were first called |
aphelions | greater than 1 ua and perihelions less than 1 ua |
433 Eros | comes within 21 millionkm (13 million mi) of earth |
comets | often visible without a telescope |
Edmund Halley | one of the first men to treat comets as ordinary celestial objects |
Robert Hooke | suggested that many comet sightingsin the past were probably the same comet. |
head and tail | a comet's two main parts |
nucleus and coma | the two parts of a comet's head |
nucleus | contains most of the comet's material |
ices | rocks, dust, and frozen materials are called |
fluoresce | to shine the way that fluorescent light bulbs shine |
type I tail | is pushed away from the sun by the solar wind; mainly dust |
type II tail | is mainly dust and is pushed away from the sun by the pressure of sunlight |
periodic comet | if a comet keeps returning, it has an elliptical orbit |
Oort cloud | some evolutionary astronmers believe that there is a reservoir of comet nuclei in a region surrounding the solar system out to 50,000 ua called this |
Kuiper belt | a donut shaped region of space beyond the orbit of Uranus |
meteoroid | a particle of rock or dust in space that orbits the sun |
meteor | a glowing meteoroid that has entered earth's atmosphere |
fireball | an extra-spectacular meteor seen by obsevers over a wide area |
bolide | a meteor that appears to explode or break up violently |
train | glowing pieces that a fireball left behind them in a trail |
meorites | meteoroides that fell through the atmosphere that survive long enough to reach the ground |
sporadic meteors | meteors that come from random directions and may fall at any time |
shower meteors | meteors that are swept up by earth |
Perseids | August 12 shower meteors |
radiant | a constellation that meteors seem to radiate from |
Leonids | November 17 meteors |
Ahnighito | the largest meteorite on display at a museum |
stones or stony meteorites | the most common type of meteorites |
Irons | second most common type of meteorites |
Widmanstätten lines | irons when treated with acid |
stony-irons | about half cilicate and half iron |
chrondrules | small silicate spheres that can be seen embedded in the iron metal |
Barringer Meteorite Crater | prob. the most famous crater |
Chicxulub | found buried in sediments near the Yucatan Peninsula,Mexico in the Caribbean Sea |