Learn: Comprehensive Solar Physics: Sun's Structure, Activity, and Magnetic Cycles

The proton-proton chain requires a temperature of 100 million K to get started.

False

The solar corona is much cooler than the Sun's surface; hence we must wait for a total solar eclipse to glimpse it with the naked eye.

False

A type B9 star is hotter than a type A0.

True

Like the Sun, main sequence stars are converting hydrogen into helium in their cores.

True

The vast majority of stars near us would fall to the bottom right on the H-R diagram.

True

In a spectroscopic binary, the star whose lines shift the most weighs the most.

False

The Sun's complete classification is G2V.

True

The concept of hydrostatic equilibrium is critical to understanding how the Sun has remained stable long enough for life to evolve here.

True

Granulation is the most obvious proof of solar convective energy transport.

True

The solar corona produces a lot more X-rays than it does visible light.

True

The Sun is a fairly normal star.

True

The Sun's mass and volume are over a million times that of our Earth.

False

At very large distances from the Sun, its corona turns into the solar wind.

True

As with Uranus, the solar equator rotates slower than sunspots at higher latitudes.

False

The photosphere is about 100 times the diameter of the Earth, and large sunspots are larger than our whole planet.

True

The energy of the Sun starts as radiation, but is actually transported to its surface by convection, where it is radiated off into space at last.

True

The Sun's luminosity is greatest when there are few or no sunspots on the Sun.

False

At very large distances from the Sun, its corona turns into the solar wind.

True

The Sun's mass and volume are over a million times that of our Earth.

False

The Sun's density is about the same as Saturn's.

False

Both the gravitational and electromagnetic forces obey the inverse square law and extend infinitely outward in their effects.

True

As with Uranus, the solar equator rotates slower than sunspots at higher latitudes.

False

Sunspots are only about 2,000 K cooler than the much brighter photosphere.

True

Prominences hanging off the limb of the Sun are the same as filaments seen in front of the disk.

True

The proton-proton chain requires a temperature of 100 million K to get started.

False

Solar activity cannot disrupt communications on Earth.

False

Auroras are most brilliant during periods of increased solar activity.

True

The Sun's magnetic field has been traced out far beyond the orbit of Pluto and even Sedna.

True

We know the Sun rotates differentially by observing sunspots; as with Jupiter the solar equator rotates the fastest.

True

How long does the sunspot cycle last, on average?

About 11 years

The total light emitted by the solar corona, which is seen most effectively during a total solar eclipse, is equivalent in brightness to

the brightness of the full moon, about one millionth as bright as the solar photosphere.

A loop of gas following the magnetic field lines between sunspots' poles is:

a prominence.

Why is the solar corona so much hotter than the photosphere?

Energy is carried upward through the chromosphere by disturbed and tangled magnetic fields.

Which of these are NOT associated with the active Sun?

Granulation

The solar wind is made up primarily of

hydrogen nuclei and electrons, some He nuclei.

The solar winds blow outward from:

coronal holes.

How does the number of sunspots on the Sun vary with time?

The number of sunspots varies relatively regularly, with a period of about 11 years.

While observing the Sun, you note a large number of sunspots. What can you conclude?

There are likely to be an above average number of flares and prominences.

Where is the chromosphere on the Sun?

The chromosphere is the layer above the visible surface of the Sun.

While observing the Sun, you note a large number of sunspots. What can you conclude?

There are likely to be an above average number of flares and prominences.

Where do spicules tend to occur on the Sun?

At the boundaries of super granules

How would sunspots appear if you could magically remove them from the Sun?

They would shine bright orange in color, like Arcturus.

What are the names of the three layers in the Sun's atmosphere, in order from lowest to highest?

photosphere, chromosphere, corona

Visible sunspots lie in the:

granulation in the photosphere

Where is the coolest region in the Sun?

in the lower chromosphere

The magnetic field in a large rotating body can reverse direction periodically. For which two bodies in the solar system has evidence been found for such magnetic reversals?

Sun and Earth

How does the Sun's overall magnetic field behave?

magnetic polarity, which reverses every 11 years.

In what fundamental way does the overall solar magnetic field differ from that of Earth?

The solar field lies just beneath the surface, while Earth's field passes through the whole Earth.

What is the cause of the sunspot cycle on the Sun?

Subsurface magnetic fields are twisted by the Sun's differential rotation and break through the surface as sunspots, then gradually cancel each other and return below the surface.

During a period of high solar activity, the corona:

is more irregular.

If sunspots are cooler than the photosphere (by as much as 1500 K), what would be the peak wavelength in a sunspot spectrum compared with the peak wavelength of the photospheric spectrum?

Longer

Loops of glowing hydrogen seen hanging over the solar limb during totality are:

prominences.

The major feature that distinguishes a sunspot from other regions on the Sun is

its very powerful magnetic field.

What is a plasma?

state of matter consisting of electrons and ionized atoms

How would you describe the Sun's rotation?

The outer layers of the Sun experience differential rotation, but the inner regions rotate as a solid body.

The density of the Sun is most similar to which object?

Jupiter

The area in the Sun's atmosphere located above the chromosphere (1,500-10,000 km) where the temperature rises dramatically is called the:

Transition Zone

The luminosity of the Sun is a measure of:

the total energy emitted by the Sun in all directions.

From inside out, which is in the correct order for the structure of the Sun?

radiative zone, convective zone, chromosphere

How many planet Earths could fit inside the Sun?

a little over a million

What is the Sun's photosphere?

lowest layer of the Sun's atmosphere

The percentage (by mass) of the Sun that is Hydrogen is about:

71%

Granulation on the surface of the Sun is caused by

convective currents carrying heat from beneath the surface.

The surface of the Sun near its edge appears dimmer and cooler than at the center of the disk when viewed in visible light because we see

less deeply into the Sun near the edge than at disk center and temperature increases with depth.

The word chromosphere refers to a

layer in the Sun's atmosphere

If a star appears to move relative to other stars over a one-year period, this motion is due to the star's:

true space motion.

If a star were moved 10 times farther away, its apparent magnitude would drop by five magnitudes.

True

If a star were moved 10 times farther away, its absolute magnitude would drop five magnitudes.

False

In a spectroscopic binary system, the star showing the larger blue shift is:

less massive and approaching us at this moment.

In the H-R diagram, the bright blue-white stars that dominate the naked eye sky lie to the:

top left.

In a visual binary system with circular orbits, if in 20 years the two stars' position angles have shifted by 30 degrees, the pair's period must be:

240ars.

In what range of masses are most stars found?

0.1 to 100 solar masses

Upon what data do measurements of sizes of eclipsing binaries depend?

their Doppler shifts and durations of stages of their eclipses

What are the two most important intrinsic properties used to classify stars?

luminosity and surface temperature

The Sun's spectrum peaks in the green region (i.e., green is the most intense color in its spectrum). The spectrum of Rigel (the knee of Orion) peaks in the short-wavelength end of the visible spectrum. Compared with the Sun, Rigel is

hotter and whiter.

A star of the Sun's diameter, but twice as hot, must be 16X more luminous than the Sun.

True

The chemical makeup of the Sun's surface can be determined by

Solar spectroscopy.

Compared to the size of the Sun, in what range of sizes are nearly all stars found?

0.01 to 100 solar radii

Stars that have masses similar to the Sun's, and sizes similar to the Earth are:

white dwarfs.

Star A and star B have the same apparent magnitude. Star A is twice as distant as star B. Therefore, star A has twice the luminosity as star B.

False

Stellar parallax is the

apparent shift seen in the position of a nearby star against more distant stars as the Earth orbits the Sun.

The birth of stars is a battle between gravity and radiation pressure.

True

First magnitude Spica appears 2.5 times brighter than second magnitude Polaris.

True

The relative brightness of a star as we see it in Earth's sky is called

apparent magnitude

In comparing first magnitude Deneb with second magnitude Polaris, we find that:

Deneb appears 2.5 times brighter to us than does Polaris.

A star of apparent magnitude +4.7 appears _____ than a star of apparent magnitude +4.8.

Brighter

The star's color index is a quick way of determining its:

Temperature

The luminosity of a star is

its total energy output into all space.

On the H-R diagram, red supergiants like Betelguese lie:

at the top right.

Stars that have masses similar to the Sun's, and sizes similar to the Earth are:

white dwarfs.

How might the most common occurring stars be described, based on our stellar neighborhood?

M main sequence

On the H-R diagram, the Sun lies:

about the middle of the main sequence.

The Hertzsprung-Russell Diagram plots ________ against the spectral type or temperature.

luminosity or absolute magnitude

On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie:

at the lower left.

On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie:

at the lower left.

Shock waves from supernovae disrupt an interstellar cloud and prevent it from forming stars.

False

On the main sequence, almost all stars have radii between about 0.1 and 10 times the Sun.

True

Like the Sun, main sequence stars are converting hydrogen into helium in their cores.

True

What are the two most important intrinsic properties used to classify stars?

Luminosity and surface temperature

On the H-R diagram, white dwarfs lie Sirius B and Procyon B lie:

at the lower left.