Nuclear Fusion & Solar Activity

The Sun The sun is a very dynamic (active) place Nuclear Fusion in the core of the sun produces huge amounts of Energy This Heat Energy rises to the surface because of convection (think density) As hot material reaches the surface of the sun gasses boil and erupt on surface

Sun Spots The Sun’s magnetic field slows down the “boiling” on the photosphere (surface) of the sun This causes areas on the sun to be slightly cooler than the surrounding areas. These cooler spots are Sunspots Sunspots = cool dark regions on the sun

Sunspots, Galileo Found Them Before the invention of the telescope, the Sun was thought to be a perfect disk.   However as soon as telescopes became available, astronomers turned them to the Sun.   They discovered two things…Sunspots and blindness.  Not Galileo though. He observed only at sunset and sunrise and by projecting the light onto a screen rather than trying to look through the telescope itself.   He drew his results very carefully: Here’s one of his drawings from 1612. Sunspots

Sunspots Sunspots and their location on the sun move in a cycle of low to high activity.

Sunspot Cycles The Number of sunspots changes from year to year. How many in Jan 2001? How many in 2009? Time (Year)

The number of sunspots increases and decreases in cycles that last from 6-17 years (averaging 11 years). Solar flares accompany increases in sunspot activity. What’s the max we’ve observed?______

Solar Flares & CME’s

Other Activity on the Sun Solar Flares = Giant storms on the surface of the sun Up to 5,000,000 °C (9,000,032 °F) They send out streams of charged particles from the sun.

Solar Flares Solar Flares can reap havoc on Earth! As emissions from the sun encounter Earth, they can ignite geomagnetic storms. These geomagnetic storms can cause: electrical power outages damage to communication satellites radio communications disturbance

Increased solar emissions can also lead to a higher frequency of auroras aka the Northern Lights clip

There is evidence that Earth’s climate is affected by the solar activity cycle. Three dimensional images of the sun by space crafts such as the STEREO, have greatly enhanced our ability to follow solar storms and forecast arrival time to Earth.

Nuclear Fusion Nuclear Fusion is why the sun is sizzlin’ hot.” The Sun is about 70% hydrogen and 28% helium and 2% metals. This changes slowly over time as the Sun converts hydrogen to helium in its core. Random fact Each second about 700,000,000 tons of hydrogen are converted to about 695,000,000 tons of helium

Fusion Nuclear Fusion = The process by which 2 or more nuclei (Hydrogen) join together or fuse. This takes a huge amount of Energy because same charged nuclei repel each other When they do this a larger more massive nucleus is made (Helium). During this process Energy is produced in the form of light and heat.

Fusion, FYI Fusion (the combining of the nuclei of elements) is how all elements found in the Universe are created. If it exists, it’s because of fusion. Humans can do this somewhat unsuccessfully and for short amounts of time

The Solar Wind In addition to heat and light, the Sun also emits a low density stream of charged particles (mostly electrons and protons) known as the solar wind which propagates throughout the solar system at about 450 km/sec (approx. 1 million mph)

The Solar Wind The solar wind moves outward from the sun in a pinwheel shaped spiral pattern in a more or less steady flow.

The Solar Wind Recent data from the spacecraft Ulysses show that during the minimum of the solar cycle the solar wind emanating from the polar regions flows at nearly double the rate, 750 kilometers per second, than it does at lower latitudes. The composition of the solar wind also appears to differ in the polar regions. During the solar maximum, however, the solar wind moves at an intermediate speed.

The Solar Wind Further study of the solar wind will be done by the recently launched Wind, ACE and SOHO spacecraft from the dynamically stable vantage point directly between the Earth and the Sun about 1.6 million km from Earth. The solar wind has large effects on the tails of comets and even has measurable effects on the trajectories of spacecraft.