FINAL FINAL 😭😭😭 Flashcards
Star
A gigantic atomic furnace where heat is generated by the conversion of hydrogen to helium.
Binary star
Two stars linked by a gravitational attraction and revolving around a common center of mass.
Lucid star
A star that can be seen with the naked eye.
Radio star
Stars that give no visible light but can be detected by radio telescopes.
Variable Star
A designation for a star that varies in brightness, with periods ranging from minutes to years.
Light year
The distance that light travels in one year, about six trillion miles.
Astronomical unit
The average distance between Earth and the Sun, about 93 million miles.
Chiasm (Cheese?)
The Hebrew method of listing things in a sandwich fashion.
Nebula
A cloud of gas or dust in space. It may be luminous or dark.
Galaxy
A giant gathering of stars, gas, and dust, all bound together by gravity.
Handspan
When holding the fingers and thumb apart at the end of your outstretched arm, the degree measure from your thumb to your little finger will approximately measure 20°.
Zodiac
The twelve constellations that straddle the ecliptic, through which the sun, moon, and planets appear to move throughout the year and known from antiquity.
Decans
The thirty-six constellations that have been associated to the twelve constellations of the zodiac from antiquity.
Constellation
Stars together, a group of stars that form a picture in the night sky.
Asterism
A star pattern identifiable within a constellation, but not itself a constellation.
Astronomy
A branch of science that deals with the laws governing celestial bodies.
Astrology
A belief system in which the configuration of the sun, moon, planets, and stars are believed to influence human affairs.
Cosmology
The study of the nature and workings of the observable universe.
Cosmogony
The study of ideas about the origin and generation of the universe.
Precession
A slow periodic wobble in Earth’s axis caused by the combined gravitational pull of the Sun and Moon.
Summer solstice
Occurs when the sun is at its greatest declination from the celestial equator. The longest day of summer.
Vernal equinox
Occurs when the path of the Sun crosses the celestial equator, the beginning of spring.
Geocentricity
The belief that Earth is at the center of our solar system instead of our sun.
Heliocentricity
The belief that the sun is at the center of the solar system.
Parallax
A method whereby astronomers can measure stellar distances by measuring the apparent change in position of a nearby star due to the Earth’s orbital motion around the sun.
Parsec
The distance at which a star would have parallax of 1 arc second. It is equal to 3.26 light years.
Conjunction
The moment when two celestial objects appear to be very close to each other in the night sky.
Occultation
The covering up of one celestial body by another.
Zenith
The point on the celestial sphere directly overhead the observer.
Nadir (Nadeer)
The point opposite the zenith on the celestial sphere.
Apogee
In relation to an object orbiting Earth, the point on its orbit farthest from Earth.
Perigee
The point of closest approach to Earth of an object in Earth’s orbit.
Black hole
A celestial object so dense that no light can escape from it.
Nova
A star that brightens suddenly by several magnitudes as it partially explodes in a thermonuclear reaction.
Gravitational Time Dialation
The force that causes clocks and all physical processes to tick at different rates in different parts of the universe.
Doppler effect
A phenomenon in which the spectrum of an object changes based on its movement. When moving farther away from us it shifts to the red side, and moving closer it shifts to the blue.
Retrograde motion
The apparent westward motion of a planet relative to the stars.
Helical rising.
The rising of a celestial object just before the sun’s rising.
Milky way
A soft, glowing, and somewhat milky band of light encircling the night sky. It is the disk of the spiral galaxy in which the Sun lies as seen in the inside.
Perihelion
The point of closest approach to the sun of an object orbiting the sun.
Aphelion
For an object orbiting the Sun, the point of orbit farthest from the Sun.
Uniformitariamism
The belief that the actions of physical processes are sufficient to account for all past changes and for the present state of all things.
What is magnitude?
A logarithmic unit useful to measure the optical brightness of a celestial objects.
What is apperent magnitude?
The brightness of the star from Earth, the higher the number, the dimmer the star.
What is absolute magnitude?
The brightness that a celestial object would appear as if viewed when its 10 parsecs from earth.
Celestial sphere
Was originally a concept of every star in the sky being attached to a dome.
What are the three markings on the celestial sphere?
North celestial pole, South celestial pole, and the celestial equator.
What is right ascension?
It is measured from 0-23, with each hour being 15°.
What is declination?
Similar to latitude, from from -90 to +90.
Explain how to locate stars on the celestial sphere.
the celestial sphere is an imaginary globe that incircles the earth, which all celestial objects can be plotted on using coordinates. To locate a star, you first find it’s declination, which is the angle above or below the celestial equator. This number has a range of -90 to +90. Then, you find Right Ascension, which is how far left or right the star is on the celestial sphere. This has a range of 0-23, which represents the hours in a full rotation of the Earth.
Explain the difference between absolute and apparent magnitude.
