SunSun – Most important star to us on – Most important star to us on Earth.Earth.

The sun and all of the heavenly The sun and all of the heavenly bodies that orbit it make up our solar bodies that orbit it make up our solar

system.system.

PhotospherePhotosphere – The visible part of the – The visible part of the sun.sun.

Sunspots – dark patches that Sunspots – dark patches that are cooler than the granules are cooler than the granules

that surround them.that surround them.

SpiculeSpicule – Flame like columns of gas – Flame like columns of gas that continually erupt from the super that continually erupt from the super

granules of the photosphere that granules of the photosphere that make up the sun’s make up the sun’s chromospherechromosphere

The The chromosphere chromosphere is only visible is only visible during a solar eclipse, when the during a solar eclipse, when the

photosphere is blocked by the moonphotosphere is blocked by the moon..

Solar Flare Solar Flare – Tremendous – Tremendous bursts of energy caused by bursts of energy caused by magnetic stress within the magnetic stress within the

sun.sun.

Solar ProminencesSolar Prominences– Streams – Streams of dense gas erupting off the of dense gas erupting off the chromosphere and returning chromosphere and returning

in looplike fashion.in looplike fashion.

Corona Corona – Huge, hot blanket of – Huge, hot blanket of vapor that extends hundreds, vapor that extends hundreds,

or thousands of miles from the or thousands of miles from the surface of the sun.surface of the sun.

Like the chromosphere, only Like the chromosphere, only visible during a total eclipse.visible during a total eclipse.

Solar Wind Solar Wind – A high speed – A high speed stream of charged particles stream of charged particles

that beats against the Earth’s that beats against the Earth’s upper atmosphere.upper atmosphere.

Caused by holes in the Caused by holes in the Corona.Corona.

The sun is The sun is 93 million miles 93 million miles away, all away, all other stars are a LOT further away. So other stars are a LOT further away. So far it doesn’t even make sense to talk far it doesn’t even make sense to talk

about the distances in miles.about the distances in miles.

Makes more sense to talk about these Makes more sense to talk about these distances in distances in light yearslight years, which is the , which is the

distance light travels in one year. Light distance light travels in one year. Light travels 186,000 miles a second, or 5.9 travels 186,000 miles a second, or 5.9

trillion miles a year.trillion miles a year.

Parallax Parallax – The apparent change in the – The apparent change in the position of an object caused by the position of an object caused by the actual change in the position of the actual change in the position of the

observer.observer.

ParasecParasec - based upon the parallax - based upon the parallax measurements of star distances.measurements of star distances.

3.26 light years3.26 light years

Apparent Magnitude Apparent Magnitude – The – The brightness of a star as it appears to brightness of a star as it appears to

an observer on the earth.an observer on the earth.

Depends on Depends on actual brightness actual brightness and and distance from earth.distance from earth.

The lower the number, the brighter The lower the number, the brighter the star.the star.

Inverse Square LawInverse Square Law– The brightness of a – The brightness of a star varies inversely as the square of the star varies inversely as the square of the

distance from the star.distance from the star.

Absolute Magnitude Absolute Magnitude – the brightness the – the brightness the star would have to an observer if all star would have to an observer if all stars were equally distant from the stars were equally distant from the

Earth.Earth.

A star’s absolute magnitude depends on A star’s absolute magnitude depends on its its surface temperature surface temperature and and sizesize. .

Stars that are extremely bright for their Stars that are extremely bright for their surface temperatures and called giants surface temperatures and called giants

and supergiants because their and supergiants because their brightness is due to their size.brightness is due to their size.

Average stars are called main sequence Average stars are called main sequence or dwarfs.or dwarfs.

Stars that are dimmer than average stars Stars that are dimmer than average stars of the same temperature are called white of the same temperature are called white

dwarfs.dwarfs.

Binary Star Binary Star – Stars which are bound – Stars which are bound together by gravity, one revolves around together by gravity, one revolves around the other like the moon revolves around the other like the moon revolves around

the Earth.the Earth.

Optical Double Optical Double – A pair of – A pair of stars that appear to form a stars that appear to form a

binary star but do not.binary star but do not.

Star Clusters Star Clusters – Large stellar – Large stellar groupings.groupings.

Globular Clusters Globular Clusters – Wandering – Wandering groups of thousands, or groups of thousands, or

millions of stars.millions of stars.

Nova Nova – a star that flares up to – a star that flares up to many times its original many times its original

brightness.brightness.

Supernova Supernova – the explosion of – the explosion of a star.a star.