Exam 2 - The Minor Objects of the Solar System

What are the minor objects of the solar system?

the asteroids, meteoroids, comets, and dust

Why are the minor object irregularly shaped?

They lack enough mass and self-gravity to become spherical

What are asteroids?

Leftover metallic and rocky planetesimals from the early Solar System

Where do asteroids mostly orbit?

They mostly orbit the Sun within the asteroid belt, between Mars and Jupiter

What was the asteroid belt?

the potential orbit for a fifth terrestrial planet, but Jupiter's massive gravity disrupted the formation of such a planet, ripping apart many planetesimals and preventing accretion

What would the collision from an asteroid release if it were to collide with the Earth?

roughly one thousand times the combined nuclear arsenal of the entire world

What would the immense energy do the Earth?

This immense energy would obliterate life at and near the impact point and shatter the asteroid into hot fragments, which would rain back down, igniting global forest fires and heating the atmosphere to inhospitable temperatures. The collision would pulverize rock into dust and ash, which would be ejected into the atmosphere, blocking sunlight for months or even years. Without sunlight, plants would die, followed by herbivores and then carnivores, leading to a mass extinction event.

When was the most recent such event occured?

Around 66 million years ago, which was the extinction of the dinosaurs

In 1970, a crater was discovered in the Yucatán peninsula in Mexico, named

Chicxulub crater

Chicxulub craters rich in the elements

Iridium and osmium

What is a meteoroid?

tiny chunk of metal and rock orbiting the Sun

How are meteoroids formed?

often created when asteroids collide and chip off pieces

Many meteoroids fall toward planet Earth every day. Most of them completely burn up in

the Earth's atmosphere as they fall toward the Earth

While a meteoroid is burning in the Earth's atmosphere, this chunk of metal and rock is called a

meteor/ falling star / shooting star

A large number of meteors over the course of a few nights is called a

meteor shower or shooting star

if a meteoroid survives the burning as a meteor, the chunk of metal and rock will crash into the Earth. This is called a

meteorite

The largest meteorite on display in the entire world is at the

American Museum of Natural History in New York City

What are comets?

icy planetesimals that formed beyond the frost line in the early Solar System, where volatile ices, such as water, methane, and ammonia, could condense

Why are most comets irregularly shaped rather than spherical?

Because of their lower mass and weak self-gravity

What do comets contain?

A significant amount of volatile ice

What did Jupiter's influence do to the remaining icy planetesimals?

prevented the remaining icy planetesimals from coalescing into a fifth gas giant, leaving behind a vast collection of comets in the outer Solar System

What happens when a comet approaches the Sun?

the heat causes the volatile ice to sublimate, forming a glowing coma and a tail

What are the two categories for comets?

Short-period comets and long-period comets

What are short period comets?

Comets with orbital periods from a few decades to a few centuries, typically orbit within the plane of the Solar System, though some have slight inclinations

Where are most of the short-period comets found?

Kuiper Belt, a region beyond Neptune's orbit

What is a famous example of short period comets that does not originate from the Kuiper Belt?

Halley's Comet with a 76 year orbit

What is the Kuiper Belt?

Theorized by Gerard Kuiper, is home to many of these comets, which return to the Sun on regular, predictable paths

What is the Kuiper Belt analogous to?

The asteroid belt

What should the Kuiper Belt formed into?

A 5th jovian planet, but with less hydrogen and helium

What is a long period comet?

Comets that have orbital periods that can span millions of years, and some may even have unbound orbits, meaning they will never return after passing the Sun

What is a difference between short and long period comets?

Long period comets are not confined to the plane of the Solar System; they can approach from above or below the plane

What is the source of long period comets?

The Oort cloud

What is the Oort cloud?

a vast, spherical cloud of comets surrounding the Solar System, possibly extending up to one light-year in size

When did the Oort cloud likely formed?

when the gas giants, especially Jupiter, flung icy planetesimals outward during the early Solar System

What is a comet's tail?

As the comet continues to approach the Sun, the sublimated gases and dust form a long, glowing tail behind the comet

Why does the tail always point away from the Sun, even when the comet moves away from the Sun after perihelion?

the solar wind pushes the gases and dust away from the comet, causing the tail to always point away from the Sun

What is solar wind?

a stream of charged particles from the Sun

What are two types of tails?

Dust tail and ion tail

What are dust tails?

composed of dust particles that reflect sunlight, giving it a yellowish appearance

What are ion tails?

consists of charged particles that are pushed away by the solar wind, giving it a bluish appearance

When the comet is moving toward the Sun on its orbit, its two tails point

behind it

When are the coma and tail only visible?

when the comet is close enough to the Sun for sublimation to occur

What remains out of sight, and why?

the nucleus of the comet, as its composed of relatively dark material

What happens once the comet moves farther from the Sun?

the coma and tail dissipate as the icy material freezes back into solid ice or escapes the Sun's influence

Why are solar sails exciting?

The concept leverages the continuous, though weak, pressure of sunlight to gradually accelerate a spacecraft. As the sail moves further from the Sun, it will experience less pressure. Over time, the spacecraft's speed can increase significantly.

What are advantages of solar sails?

This form of propulsion doesn't require onboard fuel, which makes it ideal for long-term missions. Potentially reach distant targets by using only the Sun's radiation as its propulsion. In addition to sunlight, solar sails can also be pushed by the solar winds. This combination of forces makes solar sails highly efficient in the vacuum of space, where there's no atmospheric drag to slow them down

What is one of the challenges with solar sails?

the need for extremely large, lightweight sails. They must be durable enough to withstand space's harsh conditions, like cosmic radiation and micrometeorite impacts

How long can meteor showers last?

They can last for several days or even weeks. Some are annual, meaning they occur at roughly the same time each year as Earth crosses the orbit of a specific comet

What factors impact the intensity of a meteor shower?

the size of the dust trail, the density of the particles, and the Earth's position relative to the comet's orbit

How can a long period comet impact meteor showers?

these showers are less predictable because the orbits of long-period comets are more irregular and take much longer to complete. The particles from these comets may not be as concentrated in one specific path, making meteor showers from long-period comets less frequent but still potentially impressive when they occur

What is a meteor shower named after?

named after a constellation not because the meteors appear only within that constellation, but because the constellation seems to be the source of all the meteors in the sky

When do meteor showers occur?

when meteors appear to diverge from a specific constellation in the sky, due to the Earth moving through a location within a comet's orbit

What is the meteor shower Lyrids named after and when does it occur?

Occurs in late April, caused by the Thatcher comet and named after the constellation Lyra

What is the meteor shower Perseids named after and when does it occur?

Occurs in mid-August, caused by the Swift-Tuttle comet and named after the constellation Perseus

What is the meteor shower Draconids named after and when does it occur?

Occurs in early October, caused by the Giacobini-Zinner comet and named after the constellation Draco

What is the meteor shower Orionids named after and when does it occur?

Occurs in late October, caused by the Halley comet and named after the constellation Orion

What is the meteor shower Leonids named after and when does it occur?

Occurs in mid-November, caused by the Tempel-Tuttle comet and named after the constellation Leo

What is the meteor shower Geminids named after and when does it occur?

Occurs in mid-December, caused by the Phaethon comet and named after the constellation Gemini

What is the entire plane of the Solar System filled with?

Dust

What is it called when we see at extremely dark locations, far from any city lights and other light pollution, we can see a faint glow along the zodiac constellations?

zodiac light

What is zodiac light?

sunlight reflected off the dust that fills the plane of the Solar System

Galaxies within constellations are far beyond

the stars in our Milky Way Galaxy

What is the first reason why Pluto is not a planet?

Pluto's orbit is moderately inclined to the plane of the Solar System, while the eight planets have orbits that are nearly in the same plane

What is the second reason why Pluto is not a planet?

Pluto's orbit is significantly elliptical, unlike the mostly circular orbits of the planets. While the planets have orbits with small eccentricities, Pluto's orbit has a much larger eccentricity

What is the third reason why Pluto is not a planet?

Pluto's orbit intersects Neptune's, whereas the orbits of the eight planets do not intersect

True or False: Pluto will collide with Neptune

False

When was Pluto closer to the Sun than Neptune?

Between 1979 and 1999

If Pluto were a planet, then it should be a jovian, gas-giant planet. However,

Pluto is smaller than Mercury, the smallest of the eight planets

What is Pluto primarily composed of?

Volatile ices surrounding a metallic rocky core

What is Pluto better classified as?

a short period comet in the Kuiper Belt

Pluto's largest moon Charon is practically the same size as

Pluto itself

What should the Pluto-Charon system be regarded as?

a double, short-period comet system orbiting the Sun within the Kuiper belt

What is the astronomical symbol for Pluto?

♇

What astronomical body was discovered in 1801 orbiting the Sun between Mars and Jupiter?

Ceres

What was Ceres named after?

the ancient Roman goddess of agriculture (Demeter in Greek mythology)

What was the astronomical symbol of Ceres?

⚳

After roughly fifty years of regarding Ceres as a planet

Ceres, Pallas (1802), Juno (1804), Vesta (1807) and Hygiea (1849) were demoted to minor planet and later renamed as asteroids

After roughly seventy-five years of regarding Pluto as a planet

Pluto, Varuna, Ixion and Quaoar-Weywot, Sedna, Orcus-Vanth, Eris-Dysnomia, and all these other objects were demoted to dwarf planets, and in the future will be renamed as short-period comets orbiting the Sun within the Kuiper belt.