Astronomy Flashcards
Astronomy
Astronomy is the branch of science that studies celestial objects, behaviors, and laws.
Astrology
The study of the position and movements of celestial bodies and interpreting these properties as affecting the lives of humans and nature.
Rotation
(Something) spinning around its axis/center.
Revolution
The movement of a circular object around another object.
Constellations
A constellation is a group of stars (or other celestial objects) that form a certain pattern, symbol, or animal (from the viewpoint of Earth).
Orbit
The path of a celestial object around a star, planet, or moon.
Period
In astronomy, a period refers to the time it takes for something to complete one revolution (e.g. the sun’s orbital period– orbiting the galaxy’s center).
Heliocentric
The concept of a solar system having a star at its center.
Angular Velocity
The angular velocity of a celestial body is the rate of change of its angular position.
Moon Phase
A moon phase is the shape of the sunlit portion of the moon as viewed from Earth. There are 8 main phases: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, and waning crescent.
New Moon
A new moon occurs when the moon is between the sun and Earth, causing the moon’s sunlit side to not be visible from Earth.
Full Moon
A full moon is a lunar phase during which the moon appears completely illuminated from our point of view on Earth (a complete circle in the sky). The Earth is between the moon and the sun.
Waxing
When the moon appears to be getting larger (from our vantage point on Earth).
Waning
When the sunlit side of the moon appears to be shrinking from our point of view on Earth.
Waning
When the sunlit side of the moon appears to be shrinking from our point of view on Earth.
Cresent
When the moon is visible from Earth but less than half of the side is illuminated.
Gibbous
Gibbous describes the moon as being “mostly sunlit”, or more than ½ of it being illuminated.
Quarter Moon (first & third)
A quarter moon is when half of the moon appears to be illuminated from our point of view on Earth (a quarter of the total moon, because we only ever see half of the moon). A first-quarter moon occurs when the moon is in its waxing stage (is illuminated on the right) while a third-quarter moon occurs during the moon’s waning stage (is illuminated on the left).
Solar Eclipse
A solar eclipse is when the moon is between the Earth and the sun and casts a shadow on Earth.
Lunar Eclipse
A lunar eclipse occurs when the moon is directly behind the Earth, in the Earth’s shadow, and therefore not illuminated by the sun.
Umbra
An umbra is the direct shadow of a celestial body. The place the umbra hits is completely shadowed over. For example, during a solar eclipse, the umbra region of Earth would be the area where the sun appeared completely blocked.
Penumbra
A penumbra is the indirect, or half-shadow, of a celestial body. Areas on Earth in the penumbra band during a solar eclipse would see only part of the sun obscured.
