Stars & Galaxies
Stars
Constellations
• _________________ of stars representing mythological characters, animals, or familiar objects.
• Most constellations come from the _________________.
• The stars in a constellation may appear close, however each star can be _________________ of light-years
away from each other.
• There are _________________ constellations used to divide the night sky.
_________________ Constellations
 Constellations that appear to circle around the North Star, _________________.
 These constellations are _________________ all year and never go below the horizon.
____________________________, Ursa Minor, Draco, Cepheus, Cassiopeia, Camelopardalis
_________________ Constellations
 12 constellations that line up on the _________________ with the planets.
 For about a _________________, one of these constellations is hidden behind the _________________.
_________________ & Apparent Magnitude
• Absolute Magnitude refers to the measure of _________________ that a star actually gives off.
• Apparent Magnitude refers to the _________________of light the Earth receives from the star.
Measurement in _________________
• _________________- the apparent shift in the position of an object when viewed from two different positions.
» The closer the object is to the observer, the _________________ the parallax.
Light-years- the distance light _________________in one year (9.5 trillion km in one year.)
» _________________ Centauri is the closest star to the Sun at 4.3 ly.
Properties of Stars
• Temperature- determined by the star’s “_________________” color.
From _________________to coolest:
Composition
 Observed from the light given off by the star using a ____________________________.
 A _________________ in the spectroscope divides the light into its component colors.
 The colors present/absent in the spectrum indicate the _________________ present in the star. Similar to a
fingerprint.
The Sun
The Sun’s Layers
• The Sun is a giant ball of gas/_________________.
• Core- hydrogen is fused into helium giving off massive amounts of energy (Nuclear _________________.)
above 15 million K.
• Radiative/_________________ Zones- area through which the energy travels outwards.
• Atmosphere- outermost _________________ of the Sun
The Sun’s Atmosphere
 _________________- lowest layer of the Sun’s atmosphere.
This is considered the “surface” because this is the part we see from _________________.
Sun’s photosphere is yellow at _________________K
Chromosphere- layer above the photosphere.
 _________________- highest & largest layer.
 Charged particles reach 2 _________________ K
 Core
 Radiative _________________
 Convection Zone
 Photosphere
 Sunspot
 Chromosphere
 Corona
“Surface” _________________
1. _________________- cooler dark areas
Appear & disappear regularly
Magnetic _________________
2. Prominences- huge, arching _________________ of gas.
3. ___________- violent eruptions of particles near sunspots.
4. Solar Winds- particles ejected from the Sun’s _________________.
 Bounce of the Earth’s _________________ causing the auroras.
The _________________ – An Average Star
• Middle-aged star, average absolute _________________, & average temperature.
1. _________________ star systems
 The Sun is NOT part of a multiple star _________________ unlike most stars.
2 stars is a binary system, 3 stars is a triple-star system (Alpha _________________ system)
2. Star _________________
Stars that are so close that they move _________________ as a unit.
Classifying _________________
Hetrzsprung-Russell Diagram
• Ejnar Hertzsprung & Henry Russell independently charted the _________________ between a star’s
temperature to its absolute magnitude.
• It showed that the hotter stars are also the _________________ stars, with a few _________________.
• 90% of all _________________ fit into a diagonal line in the middle of the graph (Main Sequence.)
The Main Sequence
 Contains hot, blue ________________stars that are very bright to cooler, red _________________ stars
that are very dim.
_________________, medium sized stars are in the middle of the Main Sequence like the Sun.
Dwarfs, Giants, & Supergiants
 _________________of stars are not main sequence.
Stars that are very hot (white-blue,) but are dim are called the _________________ Dwarfs.
Stars that are cooler (red-_________________,) but are very large and bright are called the Red Giants.
The _________________, coolest, & brightest stars are the Red Supergiants.
Nuclear Fusion
• Four hydrogen _________________ combine to create one helium nucleus.
• The mass of one helium nucleus is much less than 4 hydrogen nuclei, so some of the _________________
is lost in the reaction.
• The lost mass is _________________ into large amounts of energy in the form of light. (Temps in the core
exceed 15 million K)
• Evolution of Stars (_________________)
• Step 1. _________________-stars start out as clouds of dust & gas. Gravity pulls it together.
• Step 2. Protostar-the mass of gas gets bigger & bigger eventually heating up to 10 million K causing
_____________.
• Step 3. Main Sequence- when the _________________ formed by the heat balances the attraction due to
gravity it reaches _________________.
Step 4. If it has:
Small _________________
» Red dwarf stars with eventually run out of hydrogen and will collapse into a hot, White _________________.
Medium Mass
» Yellow or white stars that will run out H causing the atmosphere to _________________and cool into a Red
Giant.
» He will fuse into a _________________.
» It will eventually _________________ into a White Dwarf
Large Mass Stars
» Blue stars will expand into Red Giants when they run out of _________________ and helium fuses into
carbon.
» Carbon will then fuse into heavier & heavier elements causing the star to expand further into a Red
_________________.
When iron is formed from fusion, iron can’t be fused so the star collapses violently in a _________________.
» Depending on the mass of the core, one of the _________________ will occur:
1.) _________________ Star- smaller cores will produce a dense core of neutrons about 20km in diameter.
2.) Black Hole- larger cores will collapse to a super dense _________________. The gravity near this mass is
so strong nothing can escape from it, not even light. Locate using _________________.
» _________________ Horizon is the area where nothing can escape.
Galaxies & the Universe
Galaxies
• Large group of stars, gas, and dust held together by _________________.
-_________________ Galaxies- they have spiral arms that wind outward from the center. They can be normal
or barred.
-Elliptical Galaxies- common type of galaxy that are oval or_________________shaped.
-Irregular Galaxies- _________________ that have no distinct shape.
The_________________Way
• Spiral galaxy that is about 100,000 _________________ across.
• Out solar system is located about half-way out on one of the spiral arms.
• Like many galaxies, the Milky Way has a super massive Black Hole at its _________________.
Origin of _________________
• _________________ State Theory- the Universe has always been the same as it is today.
• Oscillating Model- the Universe expands and _________________ in a cycle.
• Big _________________ Theory- the Universe started with a bang and has expanded ever since.
Expansion of the Universe
• _________________ Shift- the changing of the wavelength of sound or
light as an object gets closer or further away.
• Red Shift- as a star or _________________ gets further away from the
Earth, its light will expand (stretch) producing a longer
_________________ (red) in the spectroscope.
• Blue Shift-as a star or galaxy gets closer to the _________________, its light will get compressed (squeezed)
producing a shorter wavelength (blue) in the spectroscope.
» Most galaxies show red shift, therefore the _________________ is expanding.
The Big Bang Theory
• All energy & matter was created in an instant with an _________________ explosion.
• The matter _________________ expanded throughout space in a swirling, dense mass.
• Matter began to collect into clumps. As matter cooled, hydrogen & _________________gases formed.
• _________________ the first stars will form followed by galaxies, etc while still expanding.