Astronomy Notes – Unit 1 – Sun
WARNING: Never, ever look directly at the Sun,
especially with binoculars or telescopes!
q (1) The Sun is the nearest star to Earth, at an average distance of 93 million miles (150 million kilometers). Since the speed of light is 186,000 miles per second, it takes about 8-1/2 minutes for light from the Sun to reach the Earth.
q (2) The diameter of the Sun is 875,000 miles (1.4 million kilometers). It could hold more than one million Earths.
q (3) The surface gravity of the Sun is about 28 times that of the Earth.
q (4) The Sun produces huge amounts of energy, including light and heat, from a process called nuclear fusion. This process joins pairs of Hydrogen atoms into Helium atoms.
q (5) Scientists believe the temperature of the Sun varies from 27 million degrees Fahrenheit (15 million degrees Celsius) at the core, to 10,000 degrees Fahrenheit (5,500 degrees Celsius) at the surface, or photosphere.
q (6) The corona (Latin for crown) is the outer part of the Sun’s atmosphere, and is visible during a solar eclipse.
q (7) The Sun’s average period of rotation about its axis varies from 25 days at the equator to 36 days at higher latitudes.
q (8) A sunspot is a temporary, darker, cooler patch on the surface of the Sun. These are believed to be caused by magnetic fields that impede hot gases from rising to the surface. They last about a week or so. A typical sunspot is about the size of the Earth or larger.
q (9)
Massive, violent explosions of hot plasma on the Sun’s surface are
called solar flares. These can last from a few minutes to a few hours.
q (10) The Sun continually emits a stream of high energy, electrically charged particles called the solar wind. Near Earth, the average speed of the solar wind is about 1 million miles/hour (450 million kilometers/hour).
q (11)
The limit of the solar wind extends beyond the orbit of
q (12) The Earth’s magnetic field protects us from the solar wind. These particles cause colorful, rippling lights called aurora borealis, or northern lights near the north pole, and aurora australis, or southern lights near the south pole.
q (13) Surges in the solar wind caused by solar flares can disrupt communications and power transmission here on Earth.
q (14) Ultraviolet radiation from the Sun causes suntan and sunburn, and may be a factor in causing skin cancer.
1) Solar Wind: A continuous stream of charged particles which are released from the Sun and hurled outward into space.
2) Solar Flare: A magnetic storm on the Sun's surface which shows up as a sudden increase in brightness, ejecting hot plasma and radiation out into space.
3) Sunspot: A magnetic storm on the Sun's surface which appears as a dark area.
4) Photosphere: The visible part of the Sun’s surface
5)
6) Astronomical Unit (A.U.): The approximate distance from the Sun to the Earth which is equal to 93 million miles (150 million kilometers).
7) Solar Prominence: Gases trapped at the edge of the Sun which appear to shoot outward from the Sun's surface.
8) Nuclear Fusion: A nuclear reaction in which an element with small atoms fuses to form an element with larger atoms, releasing large amounts of energy.
9) Aurora Borealis (Northern Lights): Spectacular bands of light that sometimes shine in the night in Arctic regions due to charged particles from the Sun interacting with the Earth’s magnetic field.
10) Aurora Australis (Southern Lights): Spectacular bands of light that sometimes shine in the night in Antarctic regions due to charged particles from the Sun interacting with the Earth’s magnetic field.