NATS1745 6.0 History of Astronomy
Chapter 8 Exam Review
What was William Herschel looking for when he discovered Uranus? What made Herschel
particularly suited for discovering planets? In what 2 ways did Uranus reveal itself to
Herschel as a planet? What is it about Uranus' orbit that caused it to be considered a
planet instead of a comet? What is the origin of Uranus' name?
He was looking for new distant stars lying in the background. With every increase in
magnification the object grew. Stated it was a comet because it changed its place. The orbit was
not merely flimsy and fleeting so it was a new world in the solar system. ’Uranus’ primeval
Greek God representing the sky. Also the sun (and husband) of Gaia, the Earth.
What did Kepler believe existed between the large space between Mars and Jupiter?
Explain why Bode's Law supported this idea.
A planet. Kepler formulated laws of planetary motion which led him to this conclusion. Earth
distance tothe Sun is 10 units, the six planets of the time were 4,7,10,15,52 and 95 units from the
Sun. The large gap between Mars (15) and Jupiter (52) meant there should be a planet (28)
between the 2. planetary distances follow a numeric sequence
What is the name of the object found in 1801 between Mars and Jupiter? What was this
object finally classified as, and why? What is this object a part of?
Piazzi detected a star-like object in a near-circular orbit at the right distance from the Sun.
Finally classified as an asteroid meaning star-like because it was found to be smaller than the
moon. Circular belt containing hundreds of Asteroids b/w Mars and Jupiter.
What caused Adams and Leverrier to suspect the existence of a planet beyond Uranus?
When this planet was found, what was it named, and why?
Uranus was being pulled out of its orbit by an undiscovered planet. 1846: the planet was found
independently by French and English astronomers planet was named “Neptune” (Roman sea
God), owing to its blue color.
How were the masses of Uranus and Neptune 1st measured? How do their masses compare
with the other planets? Based on the masses and sizes, what do we know about their
densities and compositions?
Neptune and Uranus largely made up of water. Neptune would outweigh 17 earths. Rocky cores
5 times heavier than our planet. Above a huge ocean of hot water, topped with a thick
atmosphere of hydrogen and methane. What is today's theory for why all the planets in our solar system orbit the Sun in the same
direction and in roughly the same plane? What is the observational evidence for this
Current Theory: after the Sun was born from a spinning, collapsing gas cloud, and the
remaining gaseous and rocky particles in the Sun’s spinning circumstellar disk coalesced
into planets. This explains why all planets orbit in the same direction and in roughly the
same plane. The proof: disks of matter have been found around newborn stars in star-
What is today's theory for the asteroid belt? What about planetary rings?
The asteroid belt is likely leftover debris from the suns circumstellar disks that couldn’t coalesce
into a planet due to the opposing gravitational pulls of the sun and the nearby giant Jupiter
→ Asteroid belt is the debris from a failed planet
Planetary Rings are likely the leftover debris from