Crowdly

Star-forming clouds were much denser early in time

What would stars be like if carbon had the smallest mass per nuclear particle?

Supernovae would be more common

Supernovae would never occur

High-mass stars would be hotter

Who was largely responsible for the spectral classification system, and the classification of the stars in the HD catalogue?

Edward Pickering

Henry Norris Russell

Annie J Cannon

The amount of energy produced at a distance of 1 light year

Define the luminosity of a star. The luminosity is:

The amount of energy produced per second

The brightness of a star.

Which of these stars does not have fusion occurring in its core?

A red giant

A blue main-sequence star

A red main-sequence star

Which stellar clusters usually have more stars?

Open clusters

Globular clusters

Which of these layers of the Sun is coolest?

core

radiation zone

photosphere

When the Universe was 380,000 years old, its thermal radiation spectrum consisted mostly of what two types of photons?

According to the universal law of gravitation, what would happen to Earth if the Sun were somehow replaced by a black hole of the same mass?

Earth would slowly spiral into the black hole, because the black hole is the same mass as the Sun so it would not spiral in immediately.

Earth would be quickly sucked into the black hole, because the gravity around a black hole is much greater than the gravity around our Sun.

Earth’s orbit would not change, because the black hole is the same mass as the Sun.

100%

If the electromagnetic force is stronger than gravity, then why is it overpowered by gravity on large scales?

Electromagnetic force only works on tiny particles, whose mass is very small.

The electromagnetic force follows an inverse cube law with distance, rather than an inverse square law.

Most objects are electrically neutral.

100%

Electrical charge is cancelled out by mass.

The electromagnetic force only works on scales of about the size of an atomic nucleus.