2. The Sun's diameter is
864,938 miles (1,391,980
km). This is almost 10
times larger than the
planet Jupiter and about
109 times as big as the
Earth. The volume of the
Sun is 1,299,400 times
bigger than the volume
of the Earth; about
1,300,000 Earths could fit
inside the Sun
3.
4. STUDYING THE SUN
Astronomers study the Sun using special instruments.
Scientists analyze how and why the amount of light
from the Sun varies over time, the effect of the Sun's
light on the Earth's climate.
5. We have always built bridges to the sky. Our earliest ancestors were
skywatchers, making careful observations of the Sun and Moon,
making drawings and paintings and keeping count of changes on sticks
and tablets.
By the 17th century, new tools were being used to reach the sky --
telescopes were invented and discovered new worlds and a new
Universe.
Great Balls of Fire -- NOT!
Astronomers studying the Sun discovered that it is composed of gases,
not fire, and first
discovered the gas helium in the Sun's spectrum.
Many civilizations observed the rising and setting positions of the Sun
as a celestial marker -- a calendar. These changing positions could
be used to prepare for annual floods, times for planting and harvesting
and migrating to avoid inclement temperatures.
6. Telescope designs improved, and larger telescopes were
built, along with special buildings to house them --
observatories.
By the 20th century, astronomers built telescopes to study
wavelengths other than visible light, beginning with radio
telescopes.
Today, modern tools study the light -- and the reflected light --
we see from the Sun, Moon, planets, comets, and stars. We use
radio telescopes to study radio waves, space-borne gamma ray
telescopes to observe gamma rays, and other telescopes to study
everything in-between.
Ancient peoples did not all rely solely on the Sun; many also kept
track of the changing Moon -- leading to our use of the month.
The appearance of certain stars in the sky were also used as a
clock and calendar;
7. Sunspots are relatively cool, dark
patches on the sun's surface.
They come in many shapes and
sizes; they often appear in
groups. These spots are much
bigger than the Earth; they can
be over 10 times the diameter of
the Earths.
Individual sunspots only last for
one to two weeks, but the
number of sunspots follows an 11
year cycle. The current sunspot
cycle will peak in the middle of
2000. Sunspots are visible from
Earth.
The sunspot cycle was discovered
by S. Heinrich Schwabe in 1843
(he started his observations in
1826).
10. SOLAR GRANULES:
Granulation is solar granules together with
intergranular lanes (dark, cool areas between granules
where solar material is descending into the surface).
Granulation covers the visible surface (the
photosphere) of the Sun.
GRANULES:
Granules are regions of the sun where hot solar
material comes to the solar surface. Granules are about
600 miles (1,000 km) across and only exist for about 5
to 10 minutes before they fade away. It is almost as
though the surface of the Sun is bubbling like a pot of
boiling water.
11.
12. Solar faculae
A facula (plural: faculae) is literally a "bright
spot." It is used in planetary nomenclature for
naming certain surface features of planets and
moons, and is also a type of surface
phenomenon on the Sun.
Solar faculae are bright spots that form in the
canyons between solar granules, short-lived
convection cells several thousand kilometers
across that constantly form and dissipate over
timescales of several minutes. Faculae are
produced by concentrations of magnetic field
lines.
13.
14. A plage is a bright
region in
the chromosphere of
the Sun, typically
found in regions of the
chromosphere
near sunspots. The
term itself is poetically
taken from the French
word for "beach
15. SOLAR FLARES
a magnetic storm on the Sun which appears to be a
very bright spot and a gaseous surface eruption.
they are ejected thousands of miles from the surface of
the Sun.
were first observed by in 1859 by Lord Richard C.
Carrington. He wrote that as he was watching the sun
with a telescope, he saw "two patches of intensely
bright and white light" near a huge group of sunspots.
Just a few seconds later, the flare has disappeared.
17. A solar prominence (also known as a filament) is an
arc of gas that erupts from the surface of the Sun.
Prominences can loop hundreds of thousands of miles
into space.
Prominences are held above the Sun's surface by
strong magnetic fields and can last for many months.
At some time in their existence, most prominences will
erupt, spewing enormous amounts of solar material
into space.
18. Solar prominence are sheets of luminous gas emanating from the
sun’s surface – they would appear dark against the sun’s disk but
bright against the dark sky and occur in regions of horizontal
magnetic fields. Here is a NASA photo of a solar prominence.
19. The solar wind is a continuous stream
of ions (electrically charged particles) that are given
off by magnetic anomalies on the Sun.
The solar wind is emitted where the Sun's magnetic
field loops out into space instead of looping back into
the Sun. These magnetic anomalies in the Sun's corona
are called coronal holes. In X-ray photographs of the
Sun, coronal holes are black areas. Coronal holes can
last for months or years.
