Space Physics

Question 1

What is the axial tilt of the earth?

Answer 1

23.5 degrees

Question 2

What is the formula for the orbital speed of a planet?

Answer 2

v = 2πr/T

v = Orbital speed (m/s)
r = Radius of the orbit (m)
T = Time taken for an orbit (s)

Question 3

Why do seasons occur?

Answer 3

Due to a tilt of the earth’s axis that results in one side of the earth being exposed to more light than the other, causing changes in daylight hurs and temperature.

Question 4

Why are some parts of the earth colder than others?

Answer 4

This occurs because direct light that hits the middle of the earth is concentrated, givig it a large amount of thermal energy in a small area but the indirect light, carrying the same amount of energy, that hits the sides of the planet, is spread out across a larger area.

Question 5

What are the moon phases?

Answer 5

• New moon
• Crecent (waxing/waning)
• Quarter moon (first/last)
• Gibbous (waxing/waning)
• Full moon

Question 6

What are the Accretion Model Requirements?

Answer 6

• Newtonian gravity
• The presence of many different elements
• Rotation of material into an accretion disc in the same place

Question 7

What is the evidence for the Accretion Model?

Answer 7

The organisation of our solar system, and the characteristics of our planets:
- Position
- Speed
- Density

etc.

Question 8

What sort of radiation does the sun emit mainly?

Answer 8

• Infrared
• Visible light
• Ultraviolet

Question 9

What is the life cycle of a star?

Answer 9

1. Stellar Nebula, a cloud of dust and gas
2. Protostar is formed as it gains gravity
3. Main sequence star is the longest phase (for potentially billions of years) as the nuclear fusion starts and is balanced with the gravitational force
4. Star contracts as it runs out of hydrogen for fusion, then larger elements fuse and cause it to expand
5. Either Red Giant (from small/medium star) or Super Red Giant (from big star) is formed due to this expansion
6. A red giant would evetually run out of fuel when it gets to iron, then contracts to a white dwarf, eventually cooling to become a black dwarf
7. A Super red giant would eventually undergo a supernova
8. Either a neutron star is formed (from simply big star) or the entire star collapses onto itself, creating a black hole (from massive star)

Question 10

What is the length of one light year in metres?

Answer 10

9.5 x 10¹⁵m

Question 11

What can be said abut the forces that are acting in a main sequence star?

Answer 11

Fg = F of outwards pressure

Question 12

Why does Redshift occur?

Answer 12

Due to the Doppler Effect

Light wavelength is compressed or stretched depending on the observers location and relative speed

Question 13

Describe the doppler effect

Answer 13

How the observed wavelenght from a source is different to the emitted wavelenght, when there is a relative difference in speed between the source and the observer

Question 14

What is the Hubble Constant?

Answer 14

The ratio of an object’s speed in which it is movng away from earth to its distance from earth

Question 15

What is the estimated Hubble constant?

Answer 15

2.2x10^-18

Question 16

What is the main use for the Hubble Constant?

Answer 16

Used to estimate the age of the universe

Question 17

How is the relative speed of celestial objects measured?

Answer 17

By calculating its redshift

Question 18

How is the distance of calestial objects from earth measured?

Answer 18

By measuring the brightness of stars

Question 19

How is the Hubble Constant used to estimate the age of the universe?

Answer 19

v = s/t therefore t = s/v

H₀ = v/s

To use the constant to calculate the tme the universe has been epanding for, we need to rearange the formula to put it inot terms of distance/speed

H₀^-1 = s/v
= t
≈ 4.5x10¹⁷s
≈ 14 billion years

Question 20

What is the formula for the Hubble Constant?

Answer 20

H₀ = v/d

H₀ = Hubble Constant (/s)
v = Speed of object relative to earth (m/s)
d = Distance of object from earth

Question 21

What is CMBR?

Answer 21

Cosmic Microwave Background Radiation
When the universe formed, it emitted large amounts of electromagnetic radiation
Over time, as the universe expanded, this radiation has been redshifted to the microwave end of the spectrum

Question 22

Where is CMBR detected?

Answer 22

Uniformly throughout space