1. Uranus, Neptune and Pluto
Chapter 13
Uranus, Neptune and Pluto

2. How Did Astronomers discover Uranus, Neptune and Pluto

3. How Did Astronomers discover Uranus, Neptune and Pluto
Until 1781 it was believed that Saturn was the edge of the solar system
William Herschel was the first to realize that Uranus was not just a faint star
Herschel in March 1781 noticed an object that was too big and bright to be a star, he thought it was a comet, study it over several days and noticed it was moving
Herschel name the object George's star, Johann Bode named it Uranus.

4. How Did Astronomers discover Uranus, Neptune and Pluto
By 1821 the discovery of Uranus and its orbit had convinced other astronomers that there was another planet
John Couch Adams had calculated the position of the planet but astronomers could not find it in
1846
Urbain Leverrier with better calculations contacted Johann Galle of the Berlin observatory on September and it was discovered that night
The English story until 1998

5. How Did Astronomers discover Uranus, Neptune and Pluto
Percival Lowell, decided that there must be another planet, looked for it from 1905 to his death in 1916, said a wide angle telescope is what would discover this planet
Percival Lowell predicted that there was another planet that was 6m earths and 43 AU from the Sun.

6. How Did Astronomers discover Uranus, Neptune and Pluto
Clyde Tombaugh a student of Lowell, would compare photos of star backgrounds taken a week apart looking for a shifting object
Used a wide angle telescope to take photos and compare for shifting
Pluto was discovered by Clyde Tombaugh in February , named Pluto a Roman god of the underworld, the pl also relates to Percival Lowell
Was named after the Roman god of the underworld, was suggested by an 11 year old English girl

7. Why are Uranus and Neptune so different in appearance
Before voyager 2 (1986) they were considered twins
Neptune is 20% denser then Jupiter, Uranus is about the same as Jupiter
Uranus rotates on its side, temperature is not that different, North and South about the same
Uranus is uniform in color, with wind patterns similar to Earth and with little cloud cover
When we look at it now, storm cover seems to be forming, 2028 is the next solstice

9. Why are Uranus and Neptune so different in appearance
Neptune has belt and wind patterns similar to Jupiter and Saturn, Equatorial winds can reach 2200km/h (the fastest in the solar system)
Neptune has a great dark spot, that is a high pressure storm, it disappeared in 1994 and moved to the northern hemisphere
Neptune has the same internal heating as Jupiter and Saturn, Uranus does not

11. Why are Uranus and Neptune so different in appearance
Both appear to have small rocky cores, about 3% of their total mass
The core is surrounded rock and liquid, like muddy water, pressure is too low to make metallic Hydrogen
Atmospheric temps are the same, Neptune is releasing more heat then Uranus, Uranus may be better insolated
The magnetic fields are offset and continue to offer mysteries

13. Using Chapter 13 and your notes answer these questions, plus questions 1 – 5 on page 312
How did astronomers discover Uranus, Neptune, and Pluto?
Why are Uranus and Neptune so different in appearance?
Why is Neptune self-luminous whereas Uranus is not?
What do we know about the ring systems of Uranus and Neptune?
What kind of object is Pluto?