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Question 1

What reaction powers the Sun’s core?

Answer 1

Nuclear fusion in the core.

Question 2

What is the basic fusion reaction formula?

Answer 2

nucleus 1 + nucleus 2 → nucleus 3 + energy.

Question 3

Why is energy released during fusion?

Answer 3

Because the mass of products is less than the mass of reactants.

Question 4

What equation relates mass and energy in the Sun?

Answer 4

E = mc².

Question 5

What is the rest energy formula?

Answer 5

E₀ = mc².

Question 6

What is an electron volt (eV)?

Answer 6

A unit of energy equal to the energy gained by an electron when accelerated by 1 volt.

Question 7

How much energy is 1 eV in Joules?

Answer 7

1 eV = 1.602 x 10^-19 J.

Question 8

What is the energy equivalent of 1 atomic mass unit (amu)?

Answer 8

1 u = 931.5 MeV/c².

Question 9

What is the Q-value in nuclear reactions?

Answer 9

The amount of energy released or absorbed in a nuclear reaction.

Question 10

What is the Q-value of 2H + 3H → 4He + n?

Answer 10

17.5 MeV.

Question 11

Why must nuclear fusion occur at high temperatures?

Answer 11

High temperatures overcome the electrostatic repulsion between protons.

Question 12

What is the first step in the PP chain?

Answer 12

p + p → D + e⁺ + neutrino.

Question 13

What is the final step in the PP chain?

Answer 13

He-3 + He-3 → He-4 + 2p.

Question 14

What is the net result of the PP chain?

Answer 14

4 protons → He-4 + energy + 2 neutrinos + 2 positrons.

Question 15

What is the % of mass converted to energy in hydrogen fusion?

Answer 15

0.71% of the mass is converted into energy.

Question 16

How much energy is released per 1 kg of hydrogen burned?

Answer 16

6.38 x 10¹⁴ J/kg.

Question 17

How many kg of hydrogen does the Sun consume per second?

Answer 17

6 x 10¹¹ kg/s.

Question 18

How much energy is released in a single PP chain reaction in joules and MeV?

Answer 18

4.287 x 10^-12 J = 26.7 MeV.

Question 19

How much helium is produced per second in the Sun?

Answer 19

596 million tons of helium per second.

Question 20

How much mass is converted to energy per second in the Sun?

Answer 20

4 million tons converted into energy per second.

Question 21

What is the luminosity of the Sun?

Answer 21

L = 3.85 × 10²⁶ W.

Question 22

What is the solar constant?

Answer 22

1400 W/m².

Question 23

What surface area receives 500 W on Earth from sunlight?

Answer 23

A body with surface area 0.5 m².

Question 24

What is the energy production per kg of the Sun over its lifetime?

Answer 24

3 × 10¹³ J/kg over 5 billion years.

Question 25

How does the Sun maintain hydrostatic equilibrium?

Answer 25

By balancing gravitational collapse with outward pressure from fusion.

Question 26

What is the solar core's density?

Answer 26

150,000 kg/m³ (20 times iron).

Question 27

How is energy transported within the Sun?

Answer 27

Via radiation in inner zone, convection in outer zone.

Question 28

What is the photosphere?

Answer 28

The Sun’s visible surface, granulated due to convection.

Question 29

What causes sunspots and what is their temperature effect?

Answer 29

Strong magnetic fields lower temperature, appearing dark.

Question 30

What is the sunspot cycle and its duration?

Answer 30

An 11-year cycle of sunspot increase and decrease.

Question 31

What are solar prominences and solar flares?

Answer 31

Prominence = slow gas loop, flare = fast explosion of energy.

Question 32

What is the solar wind and how does it escape the Sun?

Answer 32

Through coronal holes, visible in X-rays.

Question 33

What is the solar corona and when is it visible?

Answer 33

Visible during solar eclipse when photosphere is blocked.

Question 34

What are the physical properties of the Sun (mass, radius, temp, etc.)?

Answer 34

Mass = 2x10³⁰ kg, Radius = 700,000 km, Temp = 5800 K, Luminosity = 4x10²⁶ W.

Question 35

What star is used to compare to the Sun and what are its properties?

Answer 35

Star Vega: 2.1 M☉, 2.4 R☉, 1.66 T☉, 40 L☉.

Question 36

How many Earths can fit in the Sun?

Answer 36

About 1 million Earths.

Question 37

What is the Sun's rotation period and how does it vary?

Answer 37

27-30 days, depending on latitude.

Question 38

What energy output is equivalent to the Sun’s luminosity?

Answer 38

10 billion 1-Mton bombs per second.

Question 39

How much energy does the Sun produce per second?

Answer 39

4 x 10²⁶ W.

Question 40

What is the total energy output of the Sun over 5 billion years?

Answer 40

3 x 10¹³ J/kg.