Q 01/05

Which word did Kepler coin in 1610 for the moons Galileo had found circling Jupiter?

A) Asteroids

B) Satellites

C) Planetoids

D) Moonlets

Answer · why

B) Satellites

Satellites, meaning attendants, was Kepler's word for the four bodies escorting Jupiter. Galileo had named them the Medicean Stars to flatter his patr...

Q 02/05

In which city did Kepler join Tycho Brahe in 1600 and go on to do his greatest work?

A) Copenhagen

B) Vienna

C) Prague

D) Kraków

Answer · why

C) Prague

Prague took Kepler in as a religious refugee in 1600, after he refused to change his faith to keep a teaching job. Within two years he had inherited b...

Q 03/05

Which planet's orbit did Kepler analyse under Tycho's direction, leading to his first two laws?

A) Mercury

B) Jupiter

C) Venus

D) Mars

Answer · why

D) Mars

Mars exposed the flaw in circular orbits. Kepler's best circular model still missed Tycho's observations by eight minutes of arc, and rather than blam...

Q 04/05

What shape did Kepler finally settle on for a planet's path around the Sun?

A) A perfect circle

B) An ellipse

C) A spiral

D) An egg-shaped ovoid

Answer · why

B) An ellipse

An ellipse, with the Sun at one focus. Kepler spent years on circles and then on an egg-shaped oval before finding that the true path lay midway betwe...

Q 05/05

Kepler's second law says that a line from the Sun to a planet sweeps out what?

A) Equal arcs each month

B) Equal areas in equal times

C) Equal angles in equal times

D) Equal distances each day

Answer · why

B) Equal areas in equal times

Equal areas in equal times, which means a planet has to speed up when it is near the Sun and slow down when far away. Kepler found this rule before he...