Astronomy Flashcards
What are the main pieces of evidence that we learned that supports the Big Bang theory?
- Universe is expanding
- Cosmic Microwave Background radiation
- Red shift
What are the 2 eras of the Big Bang? Summarize happened in each era.
Radiation era:
Planck epoch: no matter existed; only energy. Gravity split away from the super forces.
Grand unification epoch: strong nuclear broke away
Inflationary epoch: universe rapidly expanded; was very hot and churned with other particles.
Electroweak epoch: Forces like electromagnetic and weak finally split off
Quark epoch: the universe was still to hot & dense for subatomic particles to form
Hadron: the universe cooled down enough for quarks to bind together and form neutrons
Lepton/nuclear epoch: the protons and neutrons fused together and created an atomic nuclei, forming the first element Helium.
Matter era:
Atomic epoch: the universe cooled down enough for electrons to attach to the nuclei, called recombination, formed the second element Hydrogen.
Galactic epoch: Hydrogen and helium atoms created atomic clouds, which resulted in forming galaxies.
Stellar epoch: inside of those galaxies, stars began to form.
Summary of Radiation era: All the 4 super forces eventually split away and the universe cooled down enough for neutrons and protons to form and fuse together to create the first element helium.
Summary of Matter era: The universe eventually cooled enough to let electrons attach themselves onto the nuclei and form hydrogen. Hydrogen and helium atoms then created galaxies, and later stars.
Why is the Big Bang just a theory?
Because we cannot use our current technology and physics laws to comprehend the complex nature of this event. Unfortunately, it is impossible to rewind time back to the birth of the Big Bang to prove it.
What galaxy is our Solar System a part?
The Milky Way
What is the key process that defines all stars? Explain your understanding of this concept.
All stars are born as a nebula, which are huge clouds of dust and gas. Eventually, the clump of dust and gas gets so big that it collapses from its own gravity. The collapse causes the material at the center of the cloud to heat up-and this hot core is the beginning of a star.
- hydrogen fusing to form helium
American astronomer Edwin Hubble noticed that the light from distant galaxies was shifted toward the red part of the spectrum. What explanation did he give for this?
Because it was redshifted, that means that galaxies are spread further away from each other. This means that the universe is continuously expanding as time moves on.
Why do some stars appear to have different colours than other stars?
Because the colour of stars are directly proportional to their surface temperature. So, some stars will have different temperature than other stars, meaning their colours will appear different.
What is a spectroscope?
An instrument that separates visible lines into its spectrum.
How does the spectrum of a star relate to the Doppler Effect?
If the star is moving away from the observer, the spectrum is redshifted This will cause longer wavelengths and a decrease in frequencies. The opposite happens with blueshift.The spectrum tells us whether the star is moving away from the Earth, or getting closer. The Doppler effect have similar motives because as an object moves closer to the observer, its wavelength will become shorter and progresses longer as the object moves away.
Why do some stars appear to be brighter than others?
Due to luminosity. The closer the star to us, the brighter it appears. Size also matters, since larger stars tend to be brighter than smaller stars.
What is a Black Hole? How does a Black Hole form?
Black holes are formed when massive stars come to the end of their life. Massive stars experiences a gravitational collapse as gravity pulls in light and matter, forming a black hole.
What type of star (in terms of mass) will become a Red Giant?
Average stars.
What can be determined from a colour of a star?
The temperature, composition, and distance.
Why do spectral lines appear on the visible light spectrum for the gases present in stars?
We can use a star’s absorption spectrum to figure out what elements it is made of based on the colors of light it absorbs. There are lines present because the gases present in the Star absorbs specific wavelengths of light . Electrons get excited and moves on to a higher energy level.
Describe dark matter and cosmic microwave background
Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot.
The cosmic microwave background is the leftover radiation from the Big Bang or the time when the universe began. Since the Big Bang started off as a very hot and dense object, it is evident that there will be a faint remnant glow over time.
