EAS206 Lecture Notes - Lecture 22: Kuiper Belt, Dwarf Planet, Radial Velocity
30 Apr 2018
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Why (re)define Planet?
• 11 Kuiper belt objects that are now more than 1000 km across
• Wander across the sky
Definition of a planet
• Planet
o Poit : It’s a sphere
• Dwarf planet
o Problems – implies that planets must kick out objects or accreted them
▪ However, Earth has asteroids orbiting it
o Rogue planets = kicked out from their star and wandering around in the galaxy
o Zoe learig does’t work!
▪ Asteroids around the area of Earth or near Earth asteroids
• Alternatives?
o Gets aroud the learig of the eighorhood idea
▪ Earth WOULD be a planet
▪ Pluto is NOT
• Its large, ut if you add up all the Kuiper elt ojets, it would’t
be bigger
▪ Ceres is NOT
o Geophysical definition
▪ Orbital parameters: Regardless whether its orbiting something else or
not
▪ If its large enough to be spherical and not a star = planet
• Eg. Moon orbits EARTH and SUN
▪ Pluto is A PLANET in this case
▪ Ceres is A PLANET in this case
▪ KBOs, if large enough would be considered A PLANET
• Too many planets?
o plaets here the….
Extrasolar Planets
• Challenges
• Solutions
o Radial eloity = he a plaet’s orit auses the relatie eloity of the star to
wobble
The Kepler Mission
• Looks at a specific area of the sky and looks for TRANSITS
o Do’t hae to deal ith daytie, eather ad so a look at that area for a log
time
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Why (re)define planet: 11 kuiper belt objects that are now more than 1000 km across, wander across the sky. Its large, (cid:271)ut if you add up all the kuiper (cid:271)elt o(cid:271)je(cid:272)ts, it would(cid:374)"t be bigger: ceres is not, geophysical definition, orbital parameters: regardless whether its orbiting something else or not. If its large enough to be spherical and not a star = planet: eg. Moon orbits earth and sun: pluto is a planet in this case, ceres is a planet in this case, kbos, if large enough would be considered a planet, too many planets, (cid:1005)(cid:1005)(cid:1007) pla(cid:374)ets here the(cid:374) . Extrasolar planets: challenges, solutions, radial (cid:448)elo(cid:272)ity = (cid:449)he(cid:374) a pla(cid:374)et"s or(cid:271)it (cid:272)auses the relati(cid:448)e (cid:448)elo(cid:272)ity of the star to wobble. The kepler mission: looks at a specific area of the sky and looks for transits, do(cid:374)"t ha(cid:448)e to deal (cid:449)ith dayti(cid:373)e, (cid:449)eather a(cid:374)d so (cid:272)a(cid:374) look at that area for a lo(cid:374)g time.
