P7 - Keywords

Question 1

Solar day

Answer 1

A full 24 hours

Question 2

Retrograde motion

Answer 2

The apparent backwards motion of planets from west to east due to the combined motion of earth and the planet

Question 3

Eclipse

Answer 3

The “hiding” of one heavenly body behind another

Question 4

Ecliptic

Answer 4

The apparent path the sun traces across the sky

Question 5

Sidereal day

Answer 5

The time it takes the earth to rotate 360 degrees; 23 hours 56 minutes

Question 6

Refraction

Answer 6

The change in direction and speed of a wave as it passes from one medium to another.

Question 7

Diffraction

Answer 7

The spreading out of a wave as it passes an obstacle and expands into the region beyond the obstacle

Question 8

Frequency

Answer 8

The number of times that a wave oscillates in a second measured in Hertz

Question 9

Wavelength

Answer 9

The distance between corresponding points on two adjacent waves

Question 10

Focal point

Answer 10

The point at which all light rays parallel to the axis of the lens converge

Question 11

Focal length

Answer 11

The distance between the focal point and the lens

Question 12

Real image

Answer 12

An image produced by rays of light meeting at a point

Question 13

Angular magnification

Answer 13

A means of measuring the magnification based on the angle of rays of light from an object compared to the angle the image appears to make

Question 14

Dispersion

Answer 14

When light going through a lens is split

Question 15

Chromatic aberration

Answer 15

When different colour of light are spread around the focus and produce a blurred image

Question 16

Aperture

Answer 16

The opening of a telescope through which light enters

Question 17

Parallax

Answer 17

The apparent movement of an object ; the movement is actually caused by motion of the observer

Question 18

Light year

Answer 18

The distance light travels in a year

Question 19

Luminosity

Answer 19

The brightness of a star, dependent on its size and temperature

Question 20

Observed (or relative) intensity/ luminosity/ brightness

Answer 20

The brightness of a star from earth

Question 21

Cepheid variable

Answer 21

A star that has a changing luminosity

Question 22

Universe

Answer 22

A collection of galaxies

Question 23

Galaxy

Answer 23

A collection of stars and planets

Question 24

Nebula

Answer 24

An interstellar cloud of dust, hydrogen gas and plasma; another galaxy in the making

Question 25

Red shift

Answer 25

The shift of light towards the red part of the visible spectrum; shows that the universe is expanding

Question 26

Force

Answer 26

A push or pull acting upon an object

Question 27

Pressure

Answer 27

Force per unit area

Question 28

Absolute zero

Answer 28

The lowest temperature possible

Question 29

Radiation

Answer 29

The energy carried by gamma radiation or by a stream of particles such as neutrons, alpha particles or beta particles.

Question 30

Ionisation

Answer 30

The removal or gaining of electrons

Question 31

Gravity

Answer 31

A force of attraction between masses; the force that keeps objects orbiting larger objects

Question 32

Nuclear fusion

Answer 32

The joining together of two or more atomic nuclei to form a larger atomic nucleus

Question 33

Main sequence

Answer 33

A part of the life cycle of stars that all stars pass through

Question 34

Red giant

Answer 34

A stare that a sun-type star reaches when hydrogen fusion stops. The core collapses, heating up and causing the outer layers to expand

Question 35

Supernova

Answer 35

An exploding star

Question 36

Beau from star

Answer 36

The extremely dense remainder of some of the largest stars