ss Flashcards
Solar Nebula Theory
States that the solar system developed out of an interstellar cloud of dust and gas, called a nebula
Terrestrial Planet
Planets made of rock
Jovian Planet
Planets made of gas
Dwarf Planet
A celestial body resembling a small planet but lacking certain technical criteria that are required for it to be classed as such
Order of planets from the Sun
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Asteroid
A small rocky body orbiting the sun
Comet
A celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun
Meteoroid
A small body moving in the solar system that would become a meteor if it entered the earth’s atmosphere
Meteor
A small body of matter from outer space that enters the earth’s atmosphere, becoming incandescent as a result of friction and appearing as a streak of light
Meteorite
A meteor that survives its passage through the earth’s atmosphere such that part of it strikes the ground
Corona
The rarefied gaseous envelope of the sun; normally visible only during a total solar eclipse
Chromosphere
A reddish gaseous layer immediately above the photosphere of the sun
Photosphere
The luminous envelope of the sun from which its light and heat radiate (layer we can see)
Core
The center of the sun; densest layer; fusion occur here
Nuclear Fusion
A nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy
Constellation
A group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure
Binary star
A system of two stars in which one star revolves around the other or both revolve around a common center
Absolute Magnitude
The brightness of a celestial object as it would be seen at a standard distance of 10 parsecs (the true brightness)
Apparent Magnitude
The brightness of a celestial object as it is actually measured from the earth
Hertzsprung-Russell (HR) Diagram
The graph showing the absolute magnitude plotted against the surface temperature for a group of stars
Nebula
A cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter (birthplace of stars)
Protostar
A contracting mass of gas which represents an early stage in the formation of a star, before nucleosynthesis has begun
Main Sequence Star
A series of star types to which most stars belong, represented on a Hertzsprung–Russell diagram as a continuous band extending from the upper left (hot, bright stars) to the lower right (cool, dim stars
Red Giant star
A very large star of high luminosity and low surface temperature
White dwarf star
A small very dense star that is typically the size of a planet
Neutron star
A star of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons
Supergiant star
A very large star that is even brighter than a giant, often despite being relatively cool.
Supernova
A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
Black Hole
A region of space having a gravitational field so intense that no matter or radiation can escape
Parallax
The effect whereby the position or direction of an object appears to differ when viewed from different positions
Galaxy
A system of millions or billions of stars, together with gas and dust, held together by gravitational attractions
Red Shift
The displacement of spectral lines toward longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects (expanding)
Hubble’s Law
A law stating that the redshifts in the spectra of distant galaxies (and hence their speeds of recession) are proportional to their distance
Big Bang Theory
The universe as we know it started with an infinitely hot and dense single point that inflated and stretched — first at unimaginable speeds, and then at a more measurable rate — over the next 13.8 billion years to the still-expanding cosmos that we know today
