Space Physics Flashcards
(72 cards)
1
Q
Define solar system
A
A system of celestial bodies including:
- a star,
- planets,
- other bodies that orbit the star and
- moons that orbit the planets
2
Q
What is a celestial body? (2)
A
- Any naturally occurring object
- outside of the Earth’s atmosphere
3
Q
What path does a celestial body follow as it travels around another?
A
Orbit (circular motion)
4
Q
What is the sun
A
The star at the centre of our solar system that has a
large enough gravitational field to keep:
- planets,
- dwarf planets,
- asteroids and
- comets
in orbit around it
5
Q
What is a gravitational field?
A
The region of space around an object with mass in which another object with mass experiences a non-contact force
6
Q
What is a planet?
A
A large, spherical body in space that orbits a star
7
Q
What conditions are required for a planet to form? (2)
A
gravity must be strong enough to:
- make it spherical
- Clear its orbital path by putting other objects in its orbit
8
Q
What planets are in our solar system? (In order from sun)
A
- mercury
- venus
- earth
- mars
- Jupiter
- Saturn
- Uranus
- Neptune
9
Q
What is a dwarf planet? (2)
A
- A small spherical body that orbits a star
- but its orbital path is not clear of other objects
10
Q
What is a satellite?
A
A natural or artificial body that orbits a planet
11
Q
What is a moon?
A
A natural satellite of a planet
12
Q
What is an asteroid?
A
A small body of rock orbiting a star
13
Q
What is the asteroid belt?
A
The region of the solar system between orbits of Mars and Jupiter where many asteroids are found
14
Q
What is a comet?
A
A small body of ice, rock and dust that follows a highly elliptical orbital path around a star
(orbital path = Oval type shape, close to the sun in parts, far away in others)
15
Q
What is contained within a comet’s tail?
When is this produced?
A
- Gas and dust,
- as it passes close to a star and points away from the star
16
Q
What is a Lightyear (ly)?
A
The distance light travels in one year
17
Q
What distance does 1 ly equal?
A
9.46 x 1015 metres
18
Q
What is a nebula?
A
A large cloud of dust and gas in space
19
Q
How is a protostar formed?
A
When the core of a nebula collapses under its own gravity
20
Q
When does nuclear fusion begin in the formation of stars
A
When the core of a protostar becomes hot and dense enough for fusion to start
21
Q
What is a main sequence star?
A
A star that is in equilibrium and remains in this phase for most of its lifetime
22
Q
What forces act on a star in equilibrium? (2)
A
- gravity
- thermal expansion / radiation pressure
23
Q
What type of star is the sun
and
at what stage of life is it?
A
- a relatively small, main sequence star
- roughly in the middle of its life cycle
24
Q
When is a red giant formed? (2)
A
- when a star about the size of the sun runs out of hydrogen
- so larger nuclei form and the star expands
25
**When** is a **white dwarf** *formed*? (**2**)
- When the **nuclear reactions** in a **red giant** *stop*
- and it **starts to contract** *due to* **its own gravity**
26
**When** is a **black dwarf** *formed*?
When a **white dwarf cools** *until* it **no longer emits radiation**
27
**When** is a **red super giant** *formed*? (**2**)
- When a **star** *much larger than the sun* **runs out** of **hydrogen**
- so **larger nuclei form** and the **star expands**
28
What is a supernova?
**When** does a **supernova** *occur*?
What happens after a supernova?
(**4**)
- When a **red supergiant** *expands until it* **explodes**,
- *throwing* **hot gas** *into space* from their **outer layers**
- the **star shines** for a relatively *short time* - *brightness of 10 bn suns*
- the remaining **core may collapse more**, **some** may **become neutron stars**, *larger ones* **become black holes**
29
What is **left after** a **supernova**?
What does this depend on?
- A **neutron star** *or* a **black hole**
- depending on mass of the star at the start of its life (black hole = higher mass)
30
**Where** do *all* **naturally occurring elements** *come from*?
**Fusion reactions** in stars
31
Where do **lighter elements** (up to iron) **form**?
How?
- main sequence stars
- when hydrogen runs out, so helium nuclei start to fuse etc.
32
How do **heavier elements** (heavier than iron) **form**?
When a **supernova explodes**, throwing the elements into the universe
33
What is a **galaxy**?
a collection of **stars** (*held by*
**gravitational forces**)
34
Which galaxy do we live in?
The Milky Way
35
**How** do astronomers **investigate** the *composition* of a **planet’s atmosphere**?
By observing **light passing through** *or* **from** a *planets atmosphere* - **spectra**
36
What is **red shift**?
What is this used as evidence for?
- When **light** from *other galaxies* is **shifted** to the **red end of the spectrum**
- This can be explained as the **universe expanding** - backing up the **Big Bang theory**
37
What does a **red shift** *tell us*?
The **space** *between* the **Earth and distant galaxies** is **expanding**
38
What is the **relationship** *between* **amount of red shift** and **speed of galaxies**? (**2**)
- The **more** the **light from a distant galaxy** is **red-shifted**,
- the **faster** the **galaxy** is **moving away** *from **earth***
39
How did **red shift** *lead to* the development of the **Big Bang Theory**?
- the **further away** a **galaxy** is, the **more** *its* **light is red-shifted**
- which suggests the **Universe** is and has been **expanding** since creation
40
What is the **Big Bang Theory** *used* to **describe**?
The early stages of the Universe
41
**When** did the **Big Bang** occur?
14 billion years ago
42
What is **CMBR** *(Cosmic Microwave Background Radiation)*?
The *remains of* the **heat energy** *released from* the **Big Bang** which is *now* **spread thinly** *across* the **whole Universe**
43
**How** does **CMBR** provide **evidence** for the **Big Bang theory**?
**Microwave radiation** has been *found* from **all directions** in **space**
44
What is **gravity *needed* for**?
To maintain a **stable orbit** of **planets around** a **star** *and* **satellites around** a **planet**
45
What is an **artificial satellite**?
A **man-made object** that **orbits a planet** e.g. telecom satellites
46
What is meant by the **stable orbit** of a **satellite**? (**2**)
- When the **speed of a satellite** is **slow enough** to **stop it *flying into space***
- but **fast enough** to **stop it *falling towards the planet***
47
What is the **problem** when a **satellite** is **traveling too quickly**? (**2**)
- **Gravitational attraction** *between planet and satellite* **too weak**
- satellite **flies into space**
48
What is the **problem** when a **satellite** is **traveling too slowly**? (**2**)
- **Gravitational attraction** *between planet and satellite* **too strong**
- satellite **falls toward planet**
49
What is a **geostationary satellite**?
**How long** does it take to **orbit the Earth**?
- A satellite that **orbits the Earth** at the **same rate** as the **Earth rotates**
- 24 hours
50
What is the **position** of a **geostationary satellite** *relative to* the *Earth’s surface*?
It remains **above** the **same place** on the **Earth’s surface**
51
What is **circular motion**?
When an object **follows a circular path**, *usually at* a **constant speed**
52
What happens to **velocity** in **circular motion**?
It is **changing**, *even if* the **speed is constant** *due to direction changes*
53
What happens to **acceleration** in **circular motion**?
Is is **accelerating** because it’s **direction** *(and velocity)* is **changing**
54
What is a **centripetal force**?
In what direction does it act?
- The **resultant force** that *causes the **acceleration*** of an *object* **traveling in a circle**
- towards the centre of a circle
55
What does **gravitational attraction** provide for solar systems?
A **centripetal force** which keeps **satellites in orbit** *around **planets*** and **planets in orbit** *around **stars***
56
**How** does the **force of gravity** *between two objects* **vary** with **distance**?
The **closer** the objects are, the **stronger** the **force of gravity** between them
(or vice-versa)
57
What is the **effect** of the **magnitude of gravitational force** on **velocity**? (**3**)
- Greater force of gravity
- greater acceleration
- therefore greater velocity
58
What is the **effect** of **orbit size** on the **speed** of a **satellite**?
Objects in **small orbits** travel **faster** than objects in large orbits
59
What is **polar orbit**?
Orbit over a planet’s poles
60
**How long** does a **satellite** in **geostationary orbit** take to complete **one orbit**?
24 hours
61
At which **height above the Earth** does a **satellite** need to be at for **geostationary orbit**?
Around **36 000 km** *above sea level*
62
What is the **relationship** between **orbital speed** of *a satellite* **and** its **height** above a planet?
- further from planet’s surface
- slower it travels
63
What is the **relationship** between **orbital speed** of *a planet* **and** its **distance from the sun**?
- further from the sun
- slower it travels
64
Outline the **stages** in the **life cycle of a *small* star** - in order (**6**)
- nebula
- protostar
- main sequence star
- red giant
- white dwarf
- black dwarf
65
What **observation** allows astronomers to state that **space is expanding**?
Red shift
66
Outline the **Big Bang Theory** - in order (**4**)
- **expansion & cooling** of the universe
- **neutrons & protons** form
- *further expansion and cooling* allowed **nuclei** to **form**
- *temperature drops* & **hydrogen atoms form** from **neutrons and protons combining**
67
Why is travel to **exoplanets** not possible using modern technology
The journey is **too slow** - longer than a human life
68
What are exoplanets
Planets outside of our solar system
69
**Why** do **black holes** *appear to absorb light*? (**2**)
- there is a **strong gravitational field** in a black hole that **nothing can escape from** ,
- *including* **electromagnetic radiation** *such as* **light**
70
Outline the **stages** in the **life cycle of a *large* star** - in order (**6**)
- nebula
- protostar
- main sequence star
- red **supergiant**
- supernova
- neutron star / black hole
71
In what **type of orbit** are:
- **telecom** satellites
- **weather** satellites
- **earth observation** satellites
- geostationary
- polar
- polar
72
What **temp** is **CMBR**?
~ -270ºC
