23.2
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
constellation
group of stars that form a pattern in the sky
how many constellations are there
88
circumpolar constellation
a constellation that is always visible in the sky all year round
why cant you see some constellations all year round
earths changing position and orbit
what did ancient people use constellations for
planting, harvest and ritual celebrations
open cluster
loosely shapes groups of hundreds of stars
globular clusters
spherically shaped group of hundreds of stars
binary stars
1 of 2 stars that are bound together by gravity and orbit a common center of mass usually appear close to each other often appear as one star to the naked eye
doppler effect
an observed change in the frequency of a wave when the source or observer is moving
blue shift
the colors in the spectrum of a star moving toward the earth are shifted towards blue
light year
distance light travels in 1 year
how fast does light travel
300,000km per sec
parsec
unit of distance equal to 3.26 light years
parallax
apparent shift in the position of an object when viewed from different locations
apparent magnitude
the brightness of a star as seen from earth when compared to a magnitude scale
the ________ number a star has on the magnitude scale the __________ the star is
lower, brighter
the ________ number a star has on the magnitude scale the __________ the star is
higher, dimmer
absolute magnitude
the brightness that a star would have at a distance 10 parsecs from earth
luminosity
energy output from the surface of a star per sec
what is luminosity measured in
watts
what stars are the hottest
blue
what stars are the coolest
red
blue stars
largest stars, 1000x the sun
red stars
smallest stars, size of earth