WHAT DO YOU THINK? How does the mass of the Sun compare with that of the rest of the Solar System? Are there stars nearer the Earth than the Sun is? What is the inside of the Sun like (don’t just say hot :P) ? What is the surface of the Sun like? What makes the Sun shine?

The Sun – Our Star

INTERIOR of the Sun – 3 layers

Layers of the Sun Sun’s interior Sun’s atmosphere Core –hydrogen fusion happens here Radiative zone – energy as radiation (as light) Convective zone – energy by convection (as heat) Photosphere – surface of the sun– emits visible light – what we see Sun’s atmosphere Chromosphere – middle layer – transparent Corona – upper layer – transparent

When we look closer, the Sun has a marbled pattern called granulation, caused by the convection of gases just beneath the photosphere.

During an eclipse, is when we can see the layers of the Sun’s atmosphere, which emits only certain wavelengths of light, resulting in a reddish appearance  chromosphere or sphere of color …hmmm….

The solar chromosphere is characterized by jets of gas extending upward called spicules.

Source of the Solar Wind THE SOLAR CORONA – Source of the Solar Wind This x-ray image shows the million-degree gases. Seen in visible light during an eclipse.

The Sun’s Magnetic Field Creates Different Features Sunspots – areas of concentrated magnetic field lines (cooler areas) Prominences – magnetic loops above sunspots, carries plasma (hot ionized gas) Flares –magnetic field lines relax and release X-rays Coronal Mass Ejections (CMEs) – twisted magnetic field lines break and release plasma (up to 4 million mph)

Sunspots Overlapping sunspots

Ionized gases trapped by magnetic fields form prominences that arc far above the solar surface. Sometimes these gases are ejected into space.

Prominences - Cooler than photosphere

Violent eruptions, solar flares, release huge amounts of X-rays.

Coronal Mass Ejections (CMEs) typically expel 2 trillion tons of plasma at up to 4 million mph. It reaches Earth 2-4 days later, and is deflected by our magnetic field. An x-ray view of a coronal mass ejection

WHAT DID YOU THINK? How does the mass of the Sun compare with that of the rest of the Solar System? The Sun contains almost all (99.85%) of the Solar System’s mass. Are there stars nearer the Earth than the Sun is? No, the Sun is our closest star. What is the inside of the sun like? The Sun is composed of hot gases.

WHAT DID YOU THINK? What is the surface of the Sun like? The Sun has no solid surface, and no solid or liquids anywhere. The surface we see is composed of hot, churning gases. What makes the Sun shine? Thermonuclear fusion in the Sun’s core

So magnets…. How does this work in our sun? Can we see evidence of this? How do we know? How does this effect the Earth?

The Sun undergoes differential rotation meaning, the rotation period of the Sun’s gases varies from 25 days near the equator to 35 days near the solar poles WAIT! WHAT? This means the the equator spins faster than the poles.

So, the magnetic field lines of the Sun become intertwined after several rotations, creating regions of intense magnetic fields and producing sunspots and other spectacular features

Sunspot cycle Each 11 years, the Sun’s magnetic field changes direction. Overall cycle is 22 years.

Sunspots are regions of intense magnetic fields

The number of sunspots on the photosphere varies over an eleven-year cycle. Sunspot Maximum Sunspot Minimum

Sunspots can be used to determine the rate of the sun’s rotation.

Sunspot cycle

The 11 yr sunspot cycle -- magnetic cycle every 22 yrs.

On the sun, coronal mass ejections occur when solar magnetic field lines snake around each other, forming the letter "S". Usually, they go past each other. But if they connect, it's like a short circuit. The mid-section breaks loose and drives out a coronal mass ejection.

Coronal Mass Ejections (CMEs) typically expel 2 trillion tons of plasma at up to 4 million mph. An x-ray view of a coronal mass ejection This creates Auroras and magnetic interference on Earth!

By following the trails of gases released during a coronal mass ejection, we can map the Sun’s magnetic field.

Maunder Minimum  Little ice age (1645-1715) ~ Global Cooling of about 0.2o C & N. Europe about 1-2o C A period of almost no sunspots that coincided with the coldest part of the Little Ice Age

Dalton minimum 1800 – 1830 ~Year without a summer 1816 The number of sunspots at the peak of the solar cycles was about 1/3 of that observed during normal solar cycles. The three solar cycles that occurred also had unusually long periods of sunspot inactivity.

The impact on global warming ? Or – our perception of it