Constellations & Observation
The Earth rotates from ______ to ______, making objects rise in the ______ and set in the ______.
The Earth rotates from west to east, making objects rise in the east and set in the west.
Longer wavelengths of light have ______ energy, while shorter wavelengths have ______ energy.
Longer wavelengths have low energy, shorter wavelengths have high energy
The Sun is made almost entirely of these two gases.
The Sun is made of hydrogen and helium.
Stars form inside these cold, dark clouds of gas and dust.
Stars form in nebulae.
Our solar system is located in this galaxy.
The Milky Way Galaxy.
Before telescopes, people studied stars mainly to do these two things.
People studied stars to tell time and find direction.
A tool that spreads light into wavelengths so astronomers can study temperature and composition.
A spectroscope.
Name the three outer layers of the Sun in order from innermost to outermost.
Photosphere, chromosphere, corona.
What is a protostar, and how does it become a visible star?
A protostar is a contracting cloud of gas/dust. When its core becomes hot enough for nuclear fusion, it becomes a visible star.
List the three main types of galaxies.
Spiral, elliptical, irregular.
This Greek astronomer identified dozens of star patterns nearly 2,000 years ago.
Ptolemy identified dozens of star patterns nearly 2,000 years ago.
Define parallax and explain what it helps astronomers measure.
Parallax is the apparent change in an object’s position when viewed from two different points. It helps measure distance to stars.
These dark splotches on the photosphere are about the size of Earth.
Sunspots
What happens when an average-mass star runs out of helium?
It sheds outer layers of gas, leaving behind a white dwarf.
What is dark matter, and what percentage of the universe is thought to be made of it?
Dark matter = invisible matter that doesn’t emit light. Makes up 90%+ of the universe’s mass.
What is a constellation, and how many official constellations are there?
A constellation is an area in the sky where stars form a perceived pattern. There are 88 constellations.
What’s the difference between apparent magnitude and absolute magnitude?
Apparent magnitude = how bright a star looks from Earth.
Absolute magnitude (luminosity) = the star’s true brightness.
Compare a prominence, a flare, and a coronal mass ejection (CME).
Prominence = loops of glowing gas.
Flare = sudden bursts of brightness/energy.
CME = huge bubbles of gas ejected from the corona.
What is a supernova, and what causes it?
A supernova is an explosion that occurs when iron builds up in the core, causing collapse.
What holds galaxies together in clusters, superclusters, and the Milky Way?
Gravity.
Name two ways constellations were useful in ancient times.
Constellations were useful for navigation and seasonal calendars/keeping time.
What do luminosity, apparent magnitude, and distance all have in common?
They are all related: luminosity, apparent magnitude, and distance together describe how bright a star appears vs. actually is.
What creates solar wind?
Solar wind is created when charged particles stream away from the Sun.
Explain the difference between the end of an average-mass star and a high-mass star.
Average star → red giant → white dwarf → planetary nebula.
High-mass star → supernova → neutron star or black hole.
What does the Big Bang theory say about the expansion of the universe?
The universe began at one point and has been expanding ever since. Galaxies move away from each other, faster the farther they are.