Who classified galaxies using the famous tuning fork diagram, and when?

Galileo Galilei in 1610 Edwin Hubble in 1926 Carl Sagan in 1980 Isaac Newton in 1687

What are elliptical galaxies like?

Smooth, oval-shaped, mostly old red and yellow stars, little gas or dust, and almost no new star formation Flat with prominent spiral arms where new stars are constantly forming Irregular in shape with intense bursts of star formation throughout Disk-shaped with a bright bar but no spiral arms and no star formation

What is the main difference between spiral galaxies labeled Sa and those labeled Sd?

Sa galaxies have tightly wound arms and a large central bulge; Sd galaxies have loosely wound arms and a small bulge Sa galaxies are smaller than Sd galaxies Sa galaxies have a bar through the center; Sd galaxies do not Sa galaxies are elliptical; Sd galaxies are irregular

What makes a barred spiral galaxy different from a regular spiral galaxy?

A barred spiral has no spiral arms at all A barred spiral has a rectangular bar of stars through the center connecting the spiral arms A barred spiral rotates in the opposite direction of regular spirals A barred spiral contains only old stars and no star-forming regions

What type of galaxy is the Milky Way?

An elliptical galaxy An irregular galaxy A lenticular galaxy A barred spiral galaxy (type SBbc)

What are lenticular (S0) galaxies?

Disk-shaped galaxies like spirals but without spiral arms and with very little star formation Very small round galaxies with only a million stars Galaxies shaped like a lens with two bright nuclei Galaxies in the process of colliding with each other

What kind of galaxy is the Large Magellanic Cloud?

A spiral galaxy similar to the Milky Way A giant elliptical galaxy An irregular galaxy with no clear structure A lenticular galaxy

Where in galaxies does most new star formation occur?

In the central bulge, where stars are most densely packed In the spiral arms, where gas and dust are compressed and cool enough to form new stars In the halo surrounding the galaxy, where dark matter is concentrated Equally distributed throughout every part of the galaxy

What are dwarf galaxies, and how do they compare to large galaxies?

Galaxies that are very young and still forming their first stars Much smaller galaxies containing millions to a few billion stars, compared to a trillion or more in large spirals Galaxies located closest to Earth Galaxies with unusually dim stars due to low metallicity

Approximately what fraction of large galaxies are elliptical?

About 15% About 75% About 50% About 1%

Which type of galaxy typically contains the most massive individual galaxies in the universe?

Irregular galaxies, because their chaotic structure allows unlimited growth Barred spiral galaxies, because the bar channels gas efficiently to the center Giant elliptical galaxies, which can contain trillions of stars and are often found at the centers of galaxy clusters Lenticular galaxies, because they combine features of both spirals and ellipticals