SP7 - astronomy

Question 1

SP7a - what is the geocentric model

Answer 1

Ptolemy’s idea (c100-170) put earth in the center of everything with the planets and the sun orbiting around it. planets moved in small circles as they orbited the earth.

Question 2

SP7a - what is the heliocentric model ?

Answer 2

Nicolaus Copernicus (1473-1543) put the sun at the Centre of the Solar System

Question 3

SP7a - how did the advancement of technology allow us to see further into space ?

Answer 3

• the invention of the telescope - (end of 16th century) - allowed scientists to see into space in greater detail and at greater range to see and find new objects
• using the telescope Galileo Galilei (1564-1642) discovered four of Jupiter’s moons - plotted movements to suggest not everything orbited the earth — Copernicus idea of heliocentric.

Question 4

SP7a - what are asteroids

Answer 4

small rocky bodies

Question 5

SP7a - what are comets

Answer 5

made mostly of ice - found using telescopes

Question 6

SP7a - how is the current model of the solar system arranged ?

Answer 6

• 8 planets, 5 dwarf planets, thousands of comets, millions of asteroids
• move in elliptical orbits around the sun
• many planets have moons orbiting them

Question 7

SP7a - what are moons ?

Answer 7

natural satellites to planets

Question 8

SP7a - how did the first astronomers study the universe ?

Answer 8

with the naked eye + drawings

Question 9

SP7a - what further inventions have allowed us to view the universe in greater detail ?

Answer 9

photography - allowed astronomers to make more detailed observations and measurements than was possible by making drawings.
computers - increased the speed and detail of which information from telescopes can be analyzed
telescopes in orbit - more detailed than ground based as no interference from dust + clouds
space probes - explore space
telescope advancements - detect different types of electromagnetic waves (objects emitting radio waves and infrared in space) - some placed in orbit as atmosphere absorbs some radiation.

Question 10

SP7b - what is gravitational field strength dependent on

Answer 10

gravitational field strength on surface of a body depends on the mass of the body and its distance from its center to its surface (radius) . the greater its mass and the smaller its radius the greater its surface gravity. field strength different on different planets because of this.
earth - 5.97 x 10(24) kg - 6371000 m radius - 9.81 g n/kg
moon - 7.34 x 10(22) kg - 1731000 m radius - 1.62 g n/kg
mars - 6.42 x 10(23) kg - 3389000 m radius - 3.71 g n/kg
ceres - 9.39 x 10(20) kg - 473000 m radius - 0.28 g n/kg

Question 11

SP7b - what are artificial satellites

Answer 11

communications and to observe the earth and space

Question 12

SP7b - what kinds of different orbits are ?

Answer 12

polar orbit - eventually pass over all parts of the earth
highly elliptical orbits - used for communication in parts of the earth near the poles
circular/geostationary - remain over one position the earth and are used for broadcasting - move at 3070 m/s
low earth orbits - need least fuel for launching satellites - 7500 m/s

Question 13

SP7b - what is the pathway of a moving object

Answer 13

a moving object would continue to move in a straight line unless forces acting upon it

Question 14

SP7b - how do gravitational forces between the earth and a satellite converge ?

Answer 14

for a satellite in orbit gravitational force at right angles between the earth and the satellite - force change direction not speed

Question 15

SP7b - how does the speed of a satellite effect the radius of its orbit

Answer 15

gravitational force larger on that of an satellite moving in low orbit greater than in high orbit. low orbit satellite has to move faster to stay in orbit or will fall towards the earth if slows down - if gains speed as falls go into lower orbit until eventually falls near atmosphere - air slows it down and falls down towards the earths surface