Astronomy Ch 14 Practice Test

It predicted that the Sun could shine for about 25 million years, but geologists had already found that Earth is much older than this.

It was important when the Sun was forming from a shrinking interstellar cloud of gas.

There is a balance within the Sun between the outward push of pressure and the inward pull of gravity.

The amount of energy released by fusion in the Sun's core equals the amount of energy radiated from the Sun's surface into space.

As the Sun was forming, gravitational contraction increased the Sun's temperature until the core become hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.

The Sun's mass is about 300,000 times the mass of the Earth.

Like all objects, the Sun emits thermal radiation with a spectrum that depends on its temperature, and the Sun's surface temperature is just right for emitting mostly visible light.

We are seeing hot gas rising and cool gas falling due to the convection that occurs beneath the surface.

The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei.

converted to an amount of energy equal to 4 million tons times the speed of light squared

Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold.

The core would heat up, fusion rates would increase, the core would re-expand.

Fusion in the Sun's core creates neutrinos.

Fusion reactions in the Sun have ceased within the past few minutes.

Fusion gradually decreases the number of independent particles in the core, allowing gravity to compress and heat the core, which in turn increases the fusion rate and the Sun's luminosity.

They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere.

The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes.

extremely hot plasma flowing along magnetic field lines

By looking for the splitting of spectral lines in the Sun's spectrum.

Earth's upper atmosphere tends to expand during solar maximum, exerting drag on satellites in low orbits

We can send a space probe into the Sun's photosphere.

Neutrinos rarely, if ever, interact with your computer.

4 1/2 billion years

5 billion years

When a star contracts in size, gravitational potential energy is converted to thermal energy.

gravitational force and outward pressure

nuclear fusion

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 consists of gas in which many or most of the atoms are ionized (missing electrons)

70% hydrogen, 28% helium, 2% other elements

Core, radiation zone, convection zone, photosphere, chromosphere, corona

watts

photosphere

5,800 K

a stream of charged particles flowing outward from the surface of the Sun

nuclear fusion of hydrogen into helium

the specific set of nuclear reactions through which the Sun fuses hydrogen into helium

4 H becomes 1 He + energy

use computer models to predict interior conditions

They have a tendency to pass through just about any material without any interactions.

a few hundred thousand years ago

Energy is transported outward by the rising of hot plasma and sinking of cooler plasma.

They are all strongly influenced by magnetic fields on the Sun.

The sunspot cycle is very steady, so that each 11-year cycle is nearly identical to every other 11-year cycle.

Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.