Sun & Nuclear Fusion
How old is the sun and what stage of life is it in right now?
The Sun is roughly 4.6 billion years old and is currently a Main Sequence phase. We know that our sun is a main sequence star because through spectral analysis, we observe the sun is composed of hydrogen and helium.
What does Hubble's law tell us about the relationship between a galaxy's distance and motion?
As distance increases, the velocity or speed a galaxy travels away increases.
What is nucleosynthesis?
Nucleosynthesis, or nuclear fusion, is the process of combining lighter elements into heavier elements.
What force is responsible for the orbits of objects in the universe?
Gravity
What causes the different phases of the moon?
The phases are caused by the moons revolution around Earth. As the moon changes it's position, the amount of light that we see reflected off the surface changes.
What is nuclear fusion and where does it happen in the sun?
Nuclear fusion is the combination of lighter atomic nuclei to form heavier nuclei, releasing a great deal of energy. Fusion happens in the Sun's core where temperature and pressure is the greatest.
How does the observation of redshift in distant galaxies provide evidence that the universe is expanding?
Redshift occurs when wavelengths of light are stretched. The doppler effect shows us that when objects travel away from an observer, the wavelengths of light or sound stretch, or increase. The wavelengths of redshifted light are stretched, which tells us that galaxies are moving away from Earth.
How do stars produce elements?
In the core of stars, nuclear fusion combines lighter elements like hydrogen into heavier elements like helium.
What is the relationship between the mass of two objects and the gravitational force between them?
The higher the mass between two objects, the stronger the gravitational force.
What are the two types of eclipses?
Solar Eclipse: When the moon passes between the Earth and sun. The moon's shadow passes across Earth.
Lunar Eclipse: When the Earth passes between the Moon and Sun. Earth's shadow is casted on the moon.
What force in the sun is responsible for atoms and nuclei to combine?
What observations show us that the universe's expansion is accelerating?
The farther we look into the universe, the greater the redshift of light is from galaxies. This tells us that galaxies are travelling away faster near the edge of the observable universe.
What is the role of a star's mass in nucleosynthesis?
The greater a star's mass is, the greater the gravity. The stronger the gravity, the faster the nuclear fusion.
How does distance between two objects affect the gravitational force between them?
The shorter the distance, the stronger the gravity. The stronger the gravity, the faster an object orbits.
What are tides and why do they change cyclically?
Tides are the rise and fall of Earth's oceans caused by the gravitational pull of the moon and sun. High tides are on both the side facing the moon, and the side facing away from the moon. They change cyclically because the Earth rotates once every 24 hours, and the moon revolves around Earth every 27.3 days.
Why does the sun need extreme heat and pressure for nuclear fusion to work?
Hotter temperatures increase the kinetic energy (movement) of atoms. With faster movement, atoms are more likely to collide. A great deal of pressure is needed to fuse or combine atoms together.
What is cosmic microwave background radiation? When was it released?
CMB is leftover energy or radiation from the beginning of the universe. When the universe was more dense, the energy was in the form of visible light, but as the universe expanded, the wavelengths stretched and are now in the form of microwave radiation.
What kind of stars can create up to iron through nuclear fusion in their cores?
High Mass stars can form heavier elements such as iron. Smaller mass stars do not have enough force of fusion to combine heavier elements like silicon into iron.
How does the gravitational force between two objects change as they get closer to each other?
As two objects get closer, the gravitational force increases.
What causes the changing seasons on Earth?
Seasons are caused by both the tilt of Earth on its axis and the orbit of Earth around the Sun. When the Earth is in a position that has the northern hemisphere tilted towards the Sun, it receives more direct sunlight (summer). On the other side of the orbit, where the northern hemisphere is facing away from the sun, it receives less direct sunlight (winter).
What will happen to the sun billions of years from now when it runs out of fuel?
Based on the star life cycles chart, because our sun is a low mass star, it will become a red giant and then collapse into a white dwarf once nuclear fusion stops.
Where did the heavier elements (carbon, oxygen, iron) come from if the big bang only created hydrogen and helium?
After the big bang, gas clouds of hydrogen and helium clumped together due to the force of gravity. As soon as the force of gravity was strong enough, the conditions allowed for fusion to happen. Fusion in the core of stars created heavier elements from the original hydrogen and helium of the universe.
What happens to the elements in a star when a star dies?
When a star collapses, there is an explosion that spreads elements outwards into a big cloud of dust. This cloud of dust is called a planetary nebula. Gravity can cause the dust to clump together and form planets like Earth! If there is enough hydrogen and helium remaining, it can fuse together to form another star!
How can changing distance between two objects in space affect their orbital speed?
If an orbit of an object is eccentric, or an oval (any eccentricity greater than 0.0), the orbital speed will NOT be consistent. When the object is slightly closer, it will travel faster. When the object is slightly further, it will travel slower.
Why do eclipses occur cyclically?
Eclipses occur when the Earth sun and moon are in perfect alignment. The moon's orbit is tilted, therefore not always passing directly between Earth and the Sun.