Solar Astronomy: The Sun's Structure, Fusion and Wind

Our nearest star: the Sun ☀️

The Sun is the star at the centre of our Solar System: a giant ball of hot **plasma** that produces energy by **nuclear fusion** in its core and pours light and heat out into space. In this module you will learn how the Sun is built, how it makes its energy, and how the **solar wind** reaches all the way to the Earth.

Never look straight at the Sun 🕶️

Looking directly at the Sun, especially through a telescope or binoculars, can cause **permanent blindness**. Astronomers observe the Sun safely in two main ways: - **Projection**: the telescope casts an image of the Sun onto a white card or screen. - **An H-alpha filter**: a special filter that passes only a narrow band of red light, revealing features such as prominences.

Inside the Sun 🔑

The Sun has layers, each with its own job:

From the centre outward 🧅

An interactive activity.

What each layer does 🔗

Where the Sun makes its energy 🔥

In which part of the Sun does nuclear fusion produce energy?

• The core
• The photosphere
• The corona
• The convective zone

Two ways energy travels out ♨️

Once energy is made in the core, it has a long journey to the surface, crossing two zones in different ways.

How fusion works 🧱

In the Sun's _____, hydrogen nuclei join together in a process called nuclear _____. They build up to form _____, and in doing so a tiny amount of _____ is converted into _____.

The Sun's outer atmosphere 🌗

Which layer is the Sun's faint outer atmosphere, seen streaming out during a total solar eclipse?

• The corona
• The core
• The photosphere
• The radiative zone

How fast does the Sun spin? 🔢

An interactive activity.

The solar wind and Earth's shield 🧲

The Sun's hot **corona** constantly streams charged particles out into space. This flow is the **solar wind**. When it reaches the Earth, most of it is deflected by our planet's magnetic field, the **magnetosphere**. Some particles are trapped in doughnut-shaped regions called the **Van Allen belts**, and some funnel down towards the poles to create the **aurorae**.

Effects of the solar wind 🌌

The solar wind is a stream of charged particles from the Sun. Select the TWO effects it causes on or near the Earth.

• Aurorae, the northern and southern lights
• Geomagnetic storms that disrupt satellites and power grids
• Ocean tides that rise and fall twice a day
• The four seasons of the year

Spot the atmosphere 🔭

An interactive activity.

Observe the Sun and stay safe 🛰️

An interactive activity.

Explain the Sun's energy 📝

An interactive activity.