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Our solar system for SQA National 5 Physics

Our solar system

This page covers the following topics:

1. The solar system
2. The planets
3. Weight and gravity difference
4. Space travel

A galaxy is a collection of miliions of stars held together by the force of gravity. The galaxy that our planet and the Sun are in is called the Milky Way. The largest object in our Solar System is the Sun. The Sun is a huge star and its gravitational field causes many other objects in the solar system to orbit around it.

Our Solar System has both artificial and natural satellites. These are objects which orbit a planet in the Solar System. Moons are natural satellites of planets. Different planets have different numbers of moons. Artifical satellites are used to obtain information about the planets they are orbitting.

The solar system

Our solar system has 8 planets, each of which orbits the Sun. All of these planets orbit their own axis as well, except for Venus and Uranus. They are ordered in the following way, starting from the closest to the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

The planets

The weight of an object is equal to the gravitational pull on it. Since the gravitational pull is different on different planets, the weight of the same object will be different in different locations. The mass of the object will always be the same. The weight is calculated using W = mg, where m is the mass of the object and g is the gravitational field strength of a planet. The gravitational field strength on Earth is approximately 9.81 Nkgโปยน.

Weight and gravity difference

The conditions in space are not appropriate for life, which makes space travel difficult. Using a spacecraft to travel to space is also expensive and difficult, making space travel even more challenging. New methods are being developped to explore life on other planets. One of the ways in which this is done is by using space probes. Spacecrafts are propelled into space by a process called ion drive. Ion thrusters ionise propellant by adding or removing electrons and thus producing ions. The risks associated with space travel are high levels of damaging radiation, long periods of isolation and a hostile living environment.

Space travel

1

Describe what the Sun is.

The Sun is the largest object in the Solar System. The Sun is a huge star and its gravitational field causes many other objects in the Solar System to orbit around it.

largest object and the only star in the Solar System

Describe what the Sun is.

2

State a challenge of space travel.

Conditions not appropriate for life/use of spacecraft is expensive and difficult.

State a challenge of space travel.

3

Which planet is furthest from the Sun?

Neptune is the planet furthest from the Sun.

Which planet is furthest from the Sun?

4

Explain how space travel may affect the mental health of a person.

The long periods of isolation associated with space travel may pose a risk to the person's mental health.

Explain how space travel may affect the mental health of a person.

5

Define what a satellite is.

A satellite is an object which orbits a planet.

Define what a satellite is.

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