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By way process does the Sun generate energy?
nuclear fusion
At the center of the Sun, nuclear fusion converts hydrogen into
helium, gamma rays, and neutrinos
Suppose you try to bring two protons close together. Because of the electromagnetic force, the two protons will
repel one another
According to modern science, approximately how old is the Sun?
4.5 billion years
What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?
gravitational force and outward gas pressure
Why do sunspots appear dark?
they are regions that are significantly cooler than the rest of the photosphere
"Energy balance" in the Sun refers to the balance between
the rate at which fusion generates energy in the Sun's core and the rate at which the Sun's surface radiates energy into space
The Sun's surface is called the
photosphere
The Sun's average surface (photosphere) temperature is about
5,800 K
What is the solar wind?
a stream of charged particles flowing outward from the surface of the Sun
The fundamental nuclear reaction occurring in the core of the Sun is
nuclear fusion of hydrogen into helium
Which planet has the highest average surface temperature, and why?
Venus (because of its dense carbon dioxide atmosphere)
Why did the solar nebula heat up as it collapsed?
As the cloud shrank, its gravitational potential energy was converted to thermal energy
What kind of material in the solar nebula could condense at temperatures as high as 1,500 K, such as existed in the inner region of the nebula?
metals
Based on our current theory of Earth's formation, the water we drink likely comes from
water bearing planetesimals that impacted Earth
In essence, the solar nebular theory states that
our solar system formed from the collapse of an interstellar cloud of gas and dust
What do we mean by the "frost line" when we discuss the formation of planets in the solar nebula?
It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense
What do we mean by "accretion" in the context of planet formation
the growth of planetesimals from smaller solid particles that collided and stuck together
According to our theory of the solar system formation, what are asteroids and comets?
leftover planetesimals that never accreted into planets
Considering only the tilt of their axis, which planet listed below would have the most extreme seasons?
Uranus
According to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size?
the law of conservation of angular momentum
How do scientists determine the age of the solar system?
radiometric dating of meteorites
When we say that the Sun is a ball of plasma, we mean that
the Sun consists of gas in which many or most of the atoms are ionized (missing electrons)
What happens to energy in the Sun's "convection zone"?
energy is transported outward by the rising of hot plasma
How can we best observe the Sun's chromosphere an corona?
The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes
Satellites in low-Earth orbits are more likely to crash to Earth when the sunspot cycle is near "solar maximum" because
Earth's upper atmosphere tends to expand during solar maximum, exerting more drag on satellites in low orbits
Which of the following best describes "convection"
It is the process in which warm material expands and rises while cool material contracts and falls
Suppose Earth's atmosphere had no greenhouse gases. This would cause Earth's average surface temperature to be
well below the freezing point of water
What is a "magnetosphere"?
a region of space around a planet in which the planet's magnetic field can affect charged particles
Why is the sky blue (on Earth)?
because molecules scatter blue light more effectively than red light
Why does the burning of fossil fuels increase the greenhouse effect on Earth?
burning releases carbon dioxide into the atmosphere
How does the Sun's mass compare to Earth's mass
The Sun's mass is about 300,000 times the mass of the Earth
Why does the Sun emit neutrinos?
fusion in the Sun's core creates neutrinos when protons turn into neutrons
Why do sunspots appear dark in pictures of the Sun?
they actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere
Approximately, what is the Sun made of (by mass)?
70% hydrogen, 28% helium, 2% other elements
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