Q 01/05

Kepler is best known for his laws describing what?

A) Planetary motion

B) Electromagnetism

C) Chemical bonding

D) Thermodynamics

Answer · why

A) Planetary motion

The three laws describe elliptical orbits, equal areas in equal times, and the link between period and distance.

Q 02/05

Which Danish astronomer did Kepler assist in Prague, inheriting his observations on his death in 1601?

A) Tycho Brahe

B) Ole Rømer

C) Nicolaus Reimers

D) Christian Longomontanus

Answer · why

A) Tycho Brahe

The two met at Benátky nad Jizerou in February 1600 and fell out within months before reconciling.

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

He never extended the analysis to other planets in Astronomia Nova because he had no calculating assistants.

Q 04/05

What shape did Kepler finally hit upon for planetary orbits in 1604, after roughly 40 failed tries?

A) A perfect circle

B) An ellipse

C) A spiral

D) An egg-shaped ovoid

Answer · why

B) An ellipse

He had assumed it was too simple a solution for earlier astronomers to have missed.

Q 05/05

Kepler's second law, formulated by late 1602, states that planets sweep 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

He reached it geometrically after first proposing that a planet's speed was inversely proportional to its distance from the Sun.