ch 14-2 beyond Neptune and Meteoroids

when was Pluto thought to explain?

• thought to be needed to explain irregularities in the orbits of Uranus and Neptune, but it turned out that there were no such irrgularites

when was Pluto discovered

• 1930

what were wobbled and irregularities believed to be caused by?

• to be caused by the gravity on an undetected 9th planet

Neptune influence was not sufficient enough to?

• account for all irregularities in Uranus rotation, even itself

Why did the predicted orbital irregularities of Uranus and Neptune disappear?

• Improved calculations and more accurate measurements showed the irregularities were not real.

Why wasn't Pluto needed to explain Uranus's orbit?

• The original calculations were wrong.

Pluto’s orbit

• is eccentric and inclined to the plane of ecliptic, tiled 7°

• elongated

• 248 orbit period

what does Pluto’s orbit cross?

• the orbit of Neptune

where does Pluto orbit?

• in Kuiper belt

What is the 3:2 orbital resonance between Pluto and Neptune?

• For every 3 orbits Neptune completes around the Sun, Pluto completes 2 orbits.

what is Pluto’s largest moon?

• Charon

  • discovered in 1978

  • orbitally locked to Pluto and about an eighth as large

• (four additional moons)

what is Pluto and Charon often referred to as?

• double dwarf planet system

what did observations of eclipses of Pluto and Charon allow?

• measurement of orbital details

what did the New Horizons mission that flew past Pluto and Charon show?

• very complex terrain

• detected Nitrogen fog in valleys

  • 90% nitrogen and 10% other molecules such as methane

what are Pluto’s four smaller moons?

• Styx

• Nix

• Kerberos

• Hydra

Pluto’s atmosphere

• thin

• consisting mostly of nitrogen and traces of methane and carbon monoxide

how does Pluto’s atmosphere behave?

• behaves seasonally

• sublimated ice when closer to sun and freezes on surface further away

• at,. high alt. blue haze

have objects been observed in the Oort cloud?

• no, it is simply too far away

have objects been observed in the Kuiper belt?

• some Kuiper belt objects (KBOs) have been observed

  • about 4000 so far

  • Pholus and Eris with its small moon Dysnomia

what are the only objects that have been observed?

• the ones that enter the inner solar system

  • direct observation not possible because it is too far

  • believe their are hundreds to thousands of objects existing in the belt

What are Trans-Neptunian Objects (TNOs)?

• Objects that orbit the Sun beyond Neptune.

Where are Trans-Neptunian Objects found?

• Beyond Neptune, mainly in the Kuiper Belt.

How do Trans-Neptunian Objects compare in size to Earth?

• They are much smaller than Earth, though some are comparable in size to the Moon.

Give examples of Trans-Neptunian Objects.

• Pluto, Eris, Haumea, and Makemake.

what are the three requirements for an object to be classified as a Planet?

1. It must orbit the Sun.

2. It must be massive enough to become nearly spherical.

3. It must have cleared its orbital neighborhood of other objects.

Why is Pluto not considered a planet?

• Pluto meets the first two requirements but has not cleared its orbital neighborhood.

what is the largest known member in the Kuiper belt?

• Pluto

  • Eris may be larger

what is the farthest known object in the solar system?

• Sedna

in 2008, icy dwarf planets beyond Neptune would be known as?

• Plutoids

what are meteoroids?

• “shooting stars”

• small rocky or metallic body consist of dust grains to 1m wide

on an average dark night how many meteors can be seen?

• a few every hour

what is the flash of the meteoroids caused by?

• heating; most meteors do not survive to reach the ground

what are the sizes of meteoroids?

• less than 100m in diameter; smaller ones are the remnants of comets that have broken up

what gives the off the glowing streak of meteoroids?

• high speeds and heat air in front of them

  • surround air ionize and meteor surface vaporize

each time a comet passes near the sun

• some cometary fragments are dislodged from the nucleus

What causes a meteor shower?

• Earth passes through debris left behind by a comet.

Why do meteor showers occur on the same date each year?

• Earth crosses the same comet debris trail at the same point in its orbit each year.

What happens to meteoroids during a meteor shower?

• They burn up in Earth's atmosphere, producing visible meteors.

When does the Perseid meteor shower occur?

• Every August, when Earth passes through debris left by Comet Swift-Tuttle.

When does the Lyrid meteor shower occur?

• Every April, when Earth passes through debris left by Comet Thatcher.

Perseids vs. Lyrids

• Perseids → August → Comet Swift-Tuttle

• Lyrids → April → Comet Thatcher

what have produced the most of the visible craters in the solar system?

• larger meteoroids are usually loners from the asteroid belt

how many craters does Earth have?

• around 200 craters

what makes impact craters hard to discern?

• erosion

• geological activity (plate tectonics) erased most of evidence of meteors

where is the largest impact crater?

• on Canada

What is the typical density of meteoroids that burn up in Earth's atmosphere?

• About 500–1000 kg/m³; they are usually comet-like in composition.

What is the typical density of meteoroids that reach Earth's surface?

• About 5000 kg/m³; they are usually asteroid-like in composition.

Which meteoroids are more likely to survive atmospheric entry?

• Dense, asteroid-like meteoroids.

What is a meteoroid?

• A small rocky or metallic object traveling through space.

What is a meteor?

• The streak of light produced when a meteoroid burns up in Earth's atmosphere.

What is a meteorite?

• A meteoroid that survives passage through the atmosphere and reaches Earth's surface.

what is the composition of most meteoroids?

• very rocky composition although a few % are composed of mainly iron and nickel

types of Meteorites: Stony

• most common 90%

• silicate rock forming (dark)

• trace: Ni and Fe metal (light)

• most primitive of all are carbonaceous

types of meteorites: iron

• metallic rements or core of early asteroids

• composed primary of iron and nickel

• durable and heavy

• unique crystal pattern when polished

types of meteorites: stony-iron

• rare

• 1-2% of recovered falls

• equal parts of iron and nickel alloy and silicate minerals

asteroid types

• S-type (silicate), M-type (metallic), and C-type (carbonaceous)

comets orbits

• Some comets have highly eccentric orbits and enter the inner solar system

where is the Kuiper belt located?

• just beyond the orbit of Neptune; a number of Kuiper belt objects have recently been observed

comets nucleus, coma, and tails

• Comet nucleus is tiny, but coma and tails can be enormous, covering 30–40°of the sky

meteors that burn up in the atmosphere are most similar to?

• comets; those that land are more like asteroids

How does a comet create a meteor shower?

• As a comet gradually breaks apart while orbiting the Sun, it leaves a trail of debris (a meteoroid swarm). When Earth encounters the swarm, the particles burn up in the atmosphere, creating a meteor shower.