| Question |
Answer |
| Achromatic Lens | Lens of a telescope - brings two selected colors to the same focus - corrects for chromatic aberration. |
| Active Galactic Nucleus | The central energy source of an active galaxy. |
| Associations | Scattered stars which move through space together but are not bound by gravity into clusters. |
| Asteroids | Collections of small rocks which are found mainly between Mars and Jupiter in an area known as the asteroid belt. |
| Astronomical Unit | The average distance from the Earth to the Sun = 1.5 X 10(8)km or 93 X 10 (6) miles |
| Aurora | A display of glowing lights which occurs because a magnetic field guilds charged particles toward the north and south magnetic poles. |
| Autumnal Equinox | The point on the celestial sphere where the Sun crosses the celestial equator moving toward the south and autumn begins in the Northern Hemisphere. |
| Binary Stars | Star pairs which orbit around a common center of mass. |
| Black Hole | A mass which has collapsed to a very small volume so that is gravity prevents the escape of all radiation. |
| Blue Shift | The shortening of the wavelengths of light observed as the source of light and the observer move toward each other. |
| Cardinal Points | Points on the horizon which are directly north, south, east and west of you as you stand on the Earth. |
| Celestial Sphere | The picturing of the sky as a giant sphere surrounding the Earth. |
| Charge-Coupled Device | An electronic imaging device formed by place about 250,000 light sensitive diodes into an array of less than 1 square inch. This device is far more sensitive than a photographic plate and can project images directly into computer memory. |
| Comet | Small icy bodies which orbit the sun and produce tails made of gas and dust as they come near to the sun. |
| Constellation | A stellar pattern or the region of the sky which it occupies which has been identified by a name which is usually related to mythology. |
| Corona | The faint outer atmosphere of the sun which is composed of ionized, low density, very hot gases. |
| Cosmic Rays | Atomic nuclei which enter the Earth's atmosphere at or near the speed of light. |
| Cosmology | The study of the origin, nature, and evolution of the universe. |
| Doppler Effect | The change in the wavelength of radiation caused by the relative radial motion f the source of the wavelength and the observer. |
| Diurnal Motion | Daily motion of the sky which is caused by the Earth's rotation as evidenced in the rising and setting of the sun or moon. |
| Electromagnetic Radiation | Changing electric and magnetic fields which travel through space and transfer energy from one place to another. |
| Evening Star | Any star visible in the sky just after sunset. |
| Hertzprung-Russell Diagram | A plot showing the intrinsic brightness of stars versus their surface temperature. |
| Light-Year | The distance which light travels in one mean solar year (approximately 9.46 trillion km) |
| Morning Star | Any star visible in the sky just before sunrise. |
| Main Sequence | The area of the Hertzprung-Russell Diagram which runs from the upper left to the lower right and contains nearly 90 percent of all stars. |
| Meteor | A small piece of matter which is heated by friction and vaporizes as it falls to Earth. |
| Meteorite | A meteor which does not fully vaporize and therefore strikes the Earth |
| Missing Mass | Unobserved mass in clusters of galaxies which is thought to produce enough gravity to bind the cluster together. |
| Nadir | The point of the celestial sphere which is directly opposite the zenith. |
| Nebula | A cloud in space made of dust and gas. |
| Nova | The sudden brightening of a star which is associated with eruptions on white dwarfs which are in binary systems, often making it appear as a "new" star. |
| Polaris | The brightest star in the constellation of Ursa Minoris (the little bear or little dipper). |
| Prominences | Eruptions on the Sun's surface which are visible during a total solar eclipse. |
| Protostar | A cloud of gas and dust which is collapsing and is destined to become a star. |
| Pulsar | The source of short and precisely timed radio bursts which are believed to be spinning neutron stars. |
| Quasar | A small powerful source of energy which is thought to be the active core of a very distant galaxy. |
| Red Dwarf | A cool star of low mass found on the lower main sequence. |
| Red Shift | The lengthening of the wavelengths of light; occurs when the source and the observer are moving away from each other. |
| Resolving Power | The ability of a lens system, such as that found in a telescope, to distinguish two points from each other. |
| Right Ascension | A coordinate used on the celestial sphere (similar to longitude). The right ascension is measured eastward from the vernal equinox. |
| Sidereal Day | The period of rotation of the Earth with respect to the stars. |
| Summer Solstice | The point on the celestial sphere when the Sun is at its most northern point and summer begins in the Northern Hemisphere. |
| Sunspots | Intense magnetic fields on the Sun which can be observed as very dark spots. |
| Supernova | The explosion of a star which is caused by the collapse of a very massive star or by the transfer of matter to a white dwarf. |
| Vernal Equinox | The point of the celestial sphere where the Sun crosses the celestial equator moving toward the north and spring begins in the Northern Hemisphere. |
| Winter Solstice | The point on the celestial sphere when the Sun is at its most southern point and winter begins in the Northern Hemisphere. |
| White Dwarf Stars | Stars which have collapsed to the size of the Earth and are cooling off slowly. |
| Zenith | The point on the sky which is directly overhead while standing on the earth. |
| Zodiac | The band of sky with twelve constellations that extends 8 degrees to either side of the ecliptic and through which the sun, moon, and planets apparently pass during the year. |
| The four smaller inner planets are: | (closest to the sun) Mercury, Venus, Earth and Mars. They are called the terrestrial planets, and are primarily composed of rock and metal. |
| The four outer planets are: | Jupiter, Saturn, Uranus and Neptune, also called the gas giants, are composed largely of hydrogen and helium and are far more massive than the terrestrials. |
| The Solar System is also home to two main belts of small bodies: | The asteroid belt, which lies between Mars and Jupiter, is composed mainly of rock and metal. The second is the Kuiper belt which lies beyond Neptune's orbit, is composed mostly of ices such as water, ammonia and methane. |
| What lies within the two main belts of the Solar System? | Within these belts, five individual objects, Ceres, Pluto, Haumea, Makemake and Eris, are recognized to be large enough to have been rounded by their own gravity, and are thus termed dwarf planets. |
| Name the 8 planets in the Solar System: | From the sun out: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. |
Ch.18 LTI-MA 509
