photosynthesis The process that green plants use to convert sunlight to energy.
plasma A high energy, high temperature form of matter. Electrons are removed from
atoms, leaving each atom with an electrical charge.
radiation Electromagnetic energy; photons.
radiative zone Layer of the Sun immediately surrounding the core; energy moves atom
to atom as electromagnetic waves.
solar flare A violent explosion on the Sun’s surface.
solar wind A stream of radiation emitted by a solar flare. The solar wind extends millions
of kilometers out into space and can even reach the Earth.
sunspots Cooler, darker areas on the Sun’s surface that have lower temperatures than
surrounding areas; sunspots usually occur in pairs.
Points to Consider
- If something were to suddenly cause nuclear fusion to stop in the Sun, how would we
know? - Are there any types of dangerous energy from the Sun? What might be affected by
them? - If the Sun is all made of gases like hydrogen and helium, how can it have layers?
Going Further - Applying Math
Have you ever wondered how to measure something that you cannot reach or touch? The
answer is that you can use simple geometry. We can measure the diameter of the Sun,
even though we cannot go to the Sun and even though the Sun is much too large for a
human being to measure. We can do this using the rules of similar triangles. The sides
of similar triangles are proportional to each other. By setting up one very small triangle
that is proportional to another, very large triangle, we can find an unknown distance or
measurement as long as we know three out of four of the parts of the equation. If you make
a pinhole in an index card and project an image of the Sun onto a clipboard held 1 meter
from the index card, the diameter of our projected image of the Sun will be proportional
to the true diameter of the Sun. Here’s the equation: s / d = S / D where s = diameter
of the projected image of the Sun, S = true diameter of the Sun. We also need to know
the true distance between the Earth and the Sun, D = 1.496 x 10^8 km and the distance (d