The Sun

Question 1

What holds sun together?

Answer 1

Sun made of gas so no rigidity. Held together by gravity

Question 2

What stops sun collapsing?

Answer 2

Thermal pressure(atoms bouncing)

Question 3

What is balance of pressure and gravity called?

Answer 3

Hydrostatic equilibrium

Question 4

Why do we need hydrostatic equilibrium?

Answer 4

•if gravity too strong sun will collapse
•if pressure too strong sun will expand

Question 5

Where is energy in sun generated?

Answer 5

The core

Question 6

Explain nuclear fusion

Answer 6

•At high T atoms bounce very fast
•so fast 4 hydrogen fuse into helium
•releases tiny amount of energy
•so much hydrogen happens a lot powering entire sun

Question 7

Where does the energy released in fusion come from?

Answer 7

Comes from binding energy of He

Question 8

What are 3 ways of transporting energy?

Answer 8

Conduction, convection, radiation

Question 9

What is radiation in sun?

Answer 9

Photons carrying energy

Question 10

What is scattering?

Answer 10

Gas so dense so photons constantly getting absorbed and re-emitted. Photons random walk outwards

Question 11

What is convection?

Answer 11

Boiling

Question 12

Explain convection in sun

Answer 12

Lower parts of sun hotter so water expands becoming less dense than stuff above it so floats upwards transporting energy to top very fast

Question 13

Ratio of radiation vs convection in sun

Answer 13

Radiation dominates lower 70%
Convection dominates upper 30%

Question 14

What is helioseismology?

Answer 14

Measure of vibration patterns on suns surface

Question 15

What is the photosphere?

Answer 15

Surface from which suns light comes to us

Question 16

What is outside the photosphere?

Answer 16

The chromosphere and the corona

Question 17

What does convection cause magnetic fields to do?

Answer 17

Bubble out of solar surface.
Sunspots and solar prominences

Question 18

What do magnetic fields do?

Answer 18

Prevent hot surrounding plasma from entering the sunspot.

Question 19

Are sunspots cooler or hotter than surrounding regions?

Answer 19

Cooler

Question 20

Typical sunspot cycle

Answer 20

10-11 years

Question 21

What happens to sunspots cycle when sun is hotter?

Answer 21

Cycle is shorter as more activity

Question 22

When is sun most active?

Answer 22

When magnetic field lines tightly wound

Question 23

What causes solar flares?

Answer 23

When magnetic field lines become too twisted they reconnect and release lots of energy

Question 24

What is solar wind?

Answer 24

Continuous flow of charged particles caused by photons streaming out and pushing a tiny bit of matter along with it

Question 25

What is CME?

Answer 25

Coronal mass ejection. Bubbles of gas erupting from solar surface

Question 26

How is earth protected from solar wind and CMEs?

Answer 26

Magnetosphere. Charged particles can’t cross magnetic field lines so solar wind deflected. Visible as aurorae

Question 27

When can one see solar corona?

Answer 27

X-rays or during solar eclipse

Question 28

How is heliosphere inflated?

Answer 28

Solar wind

Question 29

What does the heliosphere protect us from?

Answer 29

Very energetic galactic cosmic rays

Question 30

What is heliopause?

Answer 30

End of heliosphere. Where wind buffets interstellar gas