천문학 -Astronomy

Astronomy is a natural science that studies all extraterrestrial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution.
1st episode
Sun

The Sun is by far the largest object in the solar system, with an equatorial diameter of 864,000 miles (1,391,000 km). It is 109 times larger than Earth, and almost ten times the diameter of Jupiter. The Sun contains 99.86% of all matter in the Solar System, and is nearly 333,000 times more massive than the Earth.

From NASA Either of these methods will show sunspots. Sunspots are dark regions on the Sun's surface that rotate with the Sun. They can be used to track the Sun's rotation period: 25.38 days at the equator, and slower near the poles (the Sun does not rotate as a rigid sphere). Sunspots are dark because they are cooler than the surrounding areas.

Location of sun milky way

Observing the Sun
The Sun displays observable features that can be seen in small telescopes. However, one should NEVER look at the Sun through a telescope without using proper solar observing equipment. The result will most likely be permanent blindness! The Sun is best observed by projecting its image from the eyepiece onto a flat screen, or by placing a mylar filter specifically designed for solar observation over the front of the telescope tube.

Composition and Structure

The Sun is an enormous ball of gas, composed mostly of hydrogen (92.1%) and helium (7.8%). Its temperature and density vary greatly with depth from the surface. Although the Sun's average density is less than the Earth's, the Sun's core is 25 times denser than the Earth, and 150 times denser than water. The Sun's surface temperature is about 10,000°F (5500°C); but at its core, the temperature reaches 27 million degrees F (15 million degrees C).

The Sun's mass is held together by gravity, which produces the immense pressure and temperature at its core. There, these are great enough to sustain a thermonuclear fusion reaction which converts hydrogen atoms into helium. The energy produced by this reaction powers the Sun, and generates essentially all of the heat and light that we receive on Earth.

Energy generated in the Sun's core will be absorbed and re-emitted countless times by solar atoms before it reaches the surface. A single photon of light energy takes anywhere from 10,000 to 170,000 years to escape the Sun. After leaving the core, it first will pass through the radiative zone. Here, solar material is dense enough to transfer the intense heat of the core outward by thermal radiation.

When temperature drops below 2 million degrees Celsius (3.5 million degrees Fahrenheit), solar material is not dense enough to transfer energy via radiation, so convection or "boiling" occurs. In the convective zone, columns of hot material rise to the surface of the Sun; once the material cools off at the surface, it plunges back downward to the base of the convective zone, to receive more heat from the top of the radiative zone.