Q: Can you name five ways we depend on the Sun?
A: We depend on the Sun in many ways. First,
the Sun provides plants with the energy they need to grow. Plants serve as the basis for the food web, and without plants we would not be able to survive. Second, plants use the Sun, carbon dioxide, and other minerals to produce oxygen. Humans breathe oxygen, so without the Sun spurring on this cycle, we would not be able to breathe. Third, the Sun provides us with heat. Imagine how cold it would be without sunshine! Fourth, the Sun also drives the hydrologic cycle. Without this cycle, we would not have fresh water to drink. And fifth, the Sun emits energy called electromagnetic radiation. Without this radiation, we would be completely in the dark.
Q: How does the Sun stay lit?
A:The Sun is a big atomic furnace that stays lit by converting hydrogen into helium. When hydrogen atoms are fused together to form one helium atom, a tremendous amount of energy is released. The energy is so great that the Sun gives off 40,000 watts of light from every square inch of its surface!
Q: Can you identify and explain the parts of the Sun?
A:The Sun is broken down into six parts. The center of the Sun is called the core. This is where hydrogen is converted into helium. The layer above the core is the radiation zone. The outer part of the Sun's interior is called the convection zone. Above the convection zone is the photosphere. This is the part of the Sun that we see. It is the Sun's lower atmosphere. Above the photosphere is the chromosphere. It can be observed during solar eclipses when the much brighter photosphere is blocked out by the Moon. The outermost layer of the Sun is the corona. The corona extends millions of miles into space and is a million times fainter than the photosphere.
Q: What part of the Sun do we see from Earth?
A: The part of the Sun that we see from Earth is called the photosphere. It is the Sun's lower atmosphere. Although it is only a few hundred miles thick, it gives off most of its energy as visible light and heat.
Q: Why can't scientists study the Sun through X-ray telescopes on Earth?
A: Since the Earth's atmosphere absorbs X-rays,
solar X-rays can only be studied from spacecraft above our atmosphere.
Q: Besides the Soft X-ray Telescope, what other scientific instruments does Yohkoh carry and for what purposes?
A: The Soft X-ray Telescope is one of four scientific instruments carried on Yohkoh. The other three are a telescope for higher-energy X-rays and two spectrometers to study the chemical composition, temperature, and magnetic fields in the active Sun.
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By weight, the Sun is 70% hydrogen, 28% helium, 1.5% carbon, nitrogen, and oxygen, and 0.5% all other elements.
The Sun's temperature is 10,000 degrees Fahrenheit
at the surface and 27,000,000 degrees Fahrenheit at the center.
Without the Sun, the Earth would not be able to support life.
The Sun is big enough to hold over 1 million Earths.
There are many rituals and monuments devoted to worshipping the Sun and/or marking important times in the Earth's orbit around the Sun.
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chromosphere: part of the Sun that is above the photosphere. It is several thousand miles thick, but because the gases in the
chromosphere are so thin and emit very little light, the chromosphere is hard to see. It can be observed through special filters and during solar eclipses, when the much brighter photosphere is blocked out by the
Moon. The chromosphere's color is orange-red.
convection zone: a zone in a star where convection is the main mode of energy transport. A surface convective zone like the Sun's is involved in the production of its magnetic field.
corona: the outermost layer of the Sun. The corona extends millions of miles into space and is the hottest part of the surface of the Sun. It has temperatures reaching millions of degrees. Because the corona is millions of times fainter than the photosphere, it can be seen only during solar eclipses or with specially designed scientific instruments called coronagraphs.
electromagnetic radiation: energy waves with both electric and magnetic components produced by the vibration or acceleration of an electric charge. Electromagnetic radiation ranges from waves of extremely high frequency and short wavelength to extremely low frequency and long wavelength. In order of decreasing frequency, this spectrum contains gamma rays, hard and soft X-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, and radio waves
evaporation: a gradual change of a liquid into a gas without boiling. The molecules of any liquid are constantly moving. The average molecular speed depends on the temperature, but individual molecules may be moving much faster or slower than the average. At temperatures below the boiling point, faster molecules approaching the liquid's surface may have enough energy to escape as gas molecules. Because only the faster remaining molecules decreases, lowering the liquid's temperature, which depends on the average speed of the molecules.
evapotranspiration: in the hydrologic cycle, the transfer of water from the earth into
the atmosphere by (1) evaporation from surface water and soil and (2) transpiration from vegetation.
faculae: bright patches in the upper part of the solar photosphere that have a higher temperature than that of their surroundings. These faculae form shortly before sunspots.
flares: sudden short-lived brightening of small areas of the Sun's upper chromosphere/inner corona. They represent an explosive release of energy that causes a temporary heating of the surrounding area. A typical flare quickly loses its brilliance, but can last up to an hour.
grazing incidence: the degree to which X-rays reflect from a surface.
photosphere: the part of the Sun that we see. It is the Sun's lower atmosphere. The photosphere is a few hundred miles thick. It gives off most of its energy as visible light and heat.
photosynthesis: the process by which chlorophyll-containing green plants, algae, and some bacteria capture energy in the form of light and convert it to chemical energy. Virtually all the energy available for life on Earth is made available through
photosynthesis. Photosynthesis consists of two stages: a series of light-dependent reactions that are temperature-independent and a series of temperature- dependent reactions that are light-independent. The first series is called the light reaction and the second series is known as the dark reaction.
plages: bright patches in the solar chromosphere, at a higher temperature than their surroundings, that occur in areas where there is an enhancement of the relatively weak vertical magnetic field.
precipitation: in physics and chemistry, the formation of a second, visible phase of matter within a first phase. If, for example, a solution becomes supersaturated with a component that is a solid at the temperature involved, that substance crystallizes as a sediment or may be separated from the liquid phase by filtration. In some metal alloys a precipitate of one solid phase may be found within a second solid phase.
prominences: clouds of gas in the Sun's upper chromosphere / inner corona, with a high density and a lower temperature than their surroundings. When viewed against the brighter disk they appear as dark absorption features and are termed filaments.
respiration: process by which living things take in oxygen and emit carbon dioxide. Respiration also refers to the conversion by a cell of molecules such as carbohydrates and fats to energy, a process called cellular respiration. For an explanation of respiration in plants, see photosynthesis.
spicules: predominately vertical narrow jets of gas beyond the Sun's limb. Their average life span is 5-10 minutes.
sunspots: dark markings in the granulation of the solar photosphere. Sunspots are the centers of intense localized magnetic fields, and represent the most obvious manifestations of solar activity.
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