Earth & Space Science: Astronomy

Origins of the Universe - Two Main Theories

1 - Big Bang Theory 2 - Steady State Theory

Outer Planets

1 - Jupiter 2 - Saturn 3 - Uranus 4 - Neptune * Gas Giants - huge in comparison to inner planets; but less dense than the inner planets because they are not solid *Separated from inner planets by Asteroid belt

Inner Planets

1 - Mercury 2 - Venus 3 - Earth 4 - Mars *Terrestrial Planets - have solid surfaces *Separated from outer planets by Asteroid Belt

Parts of the Sun

1 - The Core 2 - The Photosphere 3 - The Chromosphere 4 - The Corona

Origins of the Solar System - Two main Hypotheses

1 - Tidal Hypothesis 2 - Condensation Hypothesis

Pulsar

A variable radio source that emits signals in very short, regular bursts, believed to be a rotating neutron star

Retrograde Rotation

The clockwise spin of a planet or moon as seen from above the planet's or moon's north pole; Venus and Uranus rotate this way

Total Solar Eclipse

When the moon lines up between the Earth and sun, blocking the sunlight; Moon is in New Moon phase when this happens

Planet

A large body in space that orbits a star

Moon

A large body that orbits a planet

In order for an astronomical body to become a Star, it must have _______________.

A mass that is greater than 7% of the mass of the Sun

Black Hole

A massive star that has collapsed and has a gravitational force so strong that light cannot escape

Absolute Magnitude

A measurement of how bright a star would appear if viewed from a set distance away

Comet

A small object/mass made of frozen gases, ice, cosmic dust, and small rocky particles that orbits the sun; most believed to originate in a dense cloud beyond Pluto; consists of a nucleus, a coma, and a tail (Tail always points away from the sun)

Earth's Revolution

Around the sun; 365 days/1 year; Determines seasonal cycle

Asteroid Belt

In between Mars and Jupiter, where most asteroids and comets can be found

Earth's Rotation

On its axis; 24 hours/1 day; Creates night and day

Ursa Minor

- Constellation - Little Bear - Contains smaller constellation: Little Dipper

V382 Cygni

- The largest stellar mass/ star - 27x the mass of the Sun

Types of Stars

Red Giants/ Supergiants, Giants, White Dwarfs, Novas, Supernovas, Neutrons

Universe

Space and all the matter and energy in it

Mars

- Surface contains numerous craters, active, and extinct volcanoes, ridges, and valleys with extremely deep fractures - Iron Oxide found in the dusty soil makes the surface seem rust-colored and the skies seem pink in color - Atmosphere: Carbon Dioxide, Nitrogen, Argon, Oxygen, and Water Vapor - Has polar regions with ice caps composed of water as well as two satellites (moons) - Named after the Roman War God

Mercury

- The closest planet to the Sun. - Its surface has craters and rocks. - Atmosphere: Hydrogen, Helium, and Sodium - Named after the Roman Messenger God

Hailey's Comet

- The most famous comet - Named after the person who first discovered it in 240 BCE - Returns to the skies near Earth every 75-76 years

Uranus

- Third largest planet in the solar system - Has retrograde revolution - A gaseous planet - Has 10 dark rings and 15 satellites - Atmosphere: Hydrogen, Helium, & Methane - Named after Greek God of the Heavens

Big Bang Theory

- Widely accepted by many astronomers - Universe originated from a magnificent explosion spreading mass, matter, and energy into space - Galaxies formed from this material as it cooled during the next half-billion years

Meteor

A burning meteoroid falling through the Earth's atmosphere; aka a Shooting Star

Supernova

A gigantic explosion in which a massive star collapses and throws its outer layers into space as it nears the end of its life cycle; Radiates even greater light energy;

Nebula

A large cloud of dust and gas formed by stars; particles in this cloud attract each other

Star

A large mass of hot, glowing gas that is hot enough and dense enough to trigger nuclear reactions and create its own energy/fuel; have different surface temperatures (as they grow, their temperature increases, as does their glow); some exist for longer periods than others

Asteroid

A large rocky body, smaller than a planet, that orbits the sun

Galaxy

A large/vast system/collection of stars, gas, and dust held together by gravity; Types: Irregular, Elliptical, Spiral

Solar Flare

A sudden eruption of intense high-energy radiation from the sun's surface; occurs when magnetic energy that has built up in the solar atmosphere is suddenly released; sudden brightness of the chromosphere; produce excited protons and electrons that shoot outward from the chromosphere at great speeds reaching Earth (these particles disturb radio reception and also affect the magnetic field on Earth)

Solar System

A system that includes a star or stars, along with plants, moons, asteroids, meteoroids, and comets, that is held together by gravity

Neutron Star

A tiny star that remains after a supernova explosion

Magnitude

Allows astronomers to rank how bright different stars appear to humans; the lower this number is, the brighter the star will appear to us; Stars in the negative range are the brightest of all

Quasar

An object that photographs like a star but has an extremely large red shift and a variable energy output; believed to be the active core of a very distant galaxy

Nova

An ordinary star that experiences a sudden increase in brightness and then fades back to its original brightness

Why do the stars appear to move across the sky each night while the pattern of stars stays the same?

As the planet rotates, the moon and stars appear to move across the sky just the way the sun does during the day; Example - Scorpius at Night and Orion during the Day

Long-Period Comets

Comets that have a period of greater than 200 years; name commonly given to comets from the Oort cloud

Short-Period Comets

Comets with periods of less than 200 years; Believed to be derived from the Kuiper Belt;

Meteoroids

Composed of particles of rock and metal of various sizes; when it travels through the Earth's atmosphere, friction causes its surface to heat up and it begins to burn

The Photosphere

Considered the surface of the Sun; also produces sunspots

Elliptical Galaxy

Consists of smooth ellipses, containing little dust and gas but composed of millions or trillions of stars

Sunspots

Cool, dark areas that can be seen on the Sun's surface

Sun's Core

Th inner portion of the Sun where nuclear fusion takes place

Why do different stars appear during different seasons?

The Earth revolves around the sun, causing different parts of the galaxy to appear during different points in the Earth's orbit; Example - Orion in the Winter and Scorpius in the Summer

Spring Equinox

The Earth's tilt is sideways toward the Sun and the hours of daylight are the same in both; Typically March 22nd

Summer Solstice

The Northern/Southern Hemisphere tilts towards the sun and receives more sunlight; Day with the most hours of sunlight and the fewest hours of darkness; June 21st

Winter Solstice

The Southern/Northern Hemisphere tilts away from the sun and receives less direct sunlight; Day with the fewest hours of sunlight; December 21

Why do planets circle the Sun?

The Sun's gravity pulls on the planets, just as Earth's gravity pulls down anything that is not held up by some other force and keeps us rooted to the ground.

Lunar Phases

The progression of the changes in the appearance of the moon over the course of a month (approx. 27 day orbit); caused by how much of the sunlit side of the Moon faces Earth; Moon's shape in the night sky changes as the moon circles the Earth

Near Side of the Moon

The same side of the moon that faces the Earth at all times

Full Moon

When the Sun and moon are on opposite sides of the Earth; moon appears to be circular because the entire illuminated half of the moon is visible; time between them is 29.53 days

The Corona

The transparent area of the Sun visible only during a total eclipse

Magnitude Stars

- 21 of the brightest stars that can be seen from Earth - First stars noticed at night - 15 commonly observed first in the Northern Hemisphere

Surface Temperature & Lifeline of Stars

Varies star to star; largely depends on their mass

Oort Cloud

- A hypothetical spherical cloud surrounding our solar system extending approximately three light years or 30 trillion kilometers from the sun - Believed to be made up of materials that were ejected from the inner solar system because of interaction with Uranus and Neptune, but are gravitationally bound to the Sun - Named after Jan Oort, who suggested its existence in 1950 - Comets from this cloud exhibit wide range of sizes, inclinations, and eccentricities - A reservoir for long-period comets

Luminosity

- A star's intrinsic brightness - The total amount of energy radiated by the star per second - Expressed in units of Watts

Gibbous Moon

- Between full and half moon, or between a half and full moon. > Waxing - only the left crescent is not illuminated > Waning - only the right crescent is not illuminated

Earth

- Considered a Water Planet, with 70% of its surface covered by water - Gravity holds the masses of water in place - Different temperatures observed on this planet allow for different states of water (solid, liquid, gas) to exist - Atmosphere: Mainly Oxygen & Nitrogen - Only known planet to support life

Ursa Major

- Constellation - aka Great Bear, Big Bear - Contains smaller constellation: Big Dipper

Neptune

- Gaseous planet - Atmosphere: Hydrogen, Helium, & Methane - 3 Rings; 2 Satellites - Named after the Roman Sea God because its atmosphere is the same color as the seas

Quarter Moon

- Half-lit moon > First Quarter - The right quarter of the moon is visible > Last Quarter - The left quarter of the moon is illuminated

Venus

- Has a slow rotation when compared to Earth - One of two planets that has retrograde Rotation - Surface of this planet is not visible due to extensive cloud cover - Atmosphere: Mostly Carbon Dioxide - Has a yelllow appearance due to sulfuric acid droplets in the dense cloud cover - Has a greater greenhouse effect than that observed on Earth - Dense clouds combined with carbon dioxide trap heat - Named after the Roman Goddess of love

Tidal Hypothesis

- Hypothesis of the origin of the Solar System - SS began with a near collision of the Sun and a large star; believed that these two stars passed each other the great gravitational pull of the large star extracted hot gases from the Sun; mass from the hot gases started to orbit the Sun, which began to coo, then condensing into the nine planets. - Supported by few astronomers

Condensation Hypothesis

- Hypothesis of the origin of the Solar System - SS began with rotating clouds of dust and gas that were squeezed together by gravitational waves that resulted from the explosion of a nearby star; condensation occurred in the center, forming the Sun, and the smaller parts of the cloud formed the nine planets - Supported by many astronomers

Jupiter

- Largest planet in the solar system - Has 16 moons - Atmosphere: Hydrogen, Helium, Methane, Ammonia - Rising Gas: White-colored bands of clouds - Descending Gases: Dark-colored bands of clouds - Gas movement caused by heat resulting from the energy of the planet's core - Has a strong magnetic field and a great red spot that is thought to be a hurricane-like cloud

Steady State Theory

- Least accepted theory - states that the Universe is continuously being renewed - Galaxies move outward and new galaxies replace the older galaxie - Astronomers have found no evidence to prove this theory

Pluto

- Once considered the smallest planet in the solar system - Planet status now being reconsidered - Atmosphere: Methane, Ammonia, Frozen Water - Has 1 Satellite - Revolves around Sun every 250 years. - Named after the Roman God of the Underworld

Saturn

- Second largest planet in the solar system - Has rings of ice, rock, and dust particles circling it - Atmosphere: Hydrogen, Helium, Methane, Ammonia - Has more than 20 satellites - Named after Roman God of agriculture

Why do stars twinkle and planets do not?

- Stars twinkle because they appear as tiny pinpoints as seen from Earth, even through telescopes. - Planets don't twinkle because they are closer, and thus appear larger in our sky, as tiny disks instead of pinpoints.

Phases of the Moon

1-New Moon 2-Waxing Crescent 3-First Quarter 4-Waxing Gibbous 5-Full Moon 6-Waning Gibbous 7-Last Quarter 8-Waning Crescent *Viewing the moon from the Southern Hemisphere causes these phases to occur in the opposite order

What is the average distance between the Earth and the Sun?

93 million miles

The Mass of Most Stars is ________.

Between 0.3 to 3.0 times the mass of the Sun.

Spiral Galaxy

Disk shaped and have extending arms that rotate around their dense centers; Example: Milky Way (Earth's Galaxy)

Solar Radiation

Energy travelling from the Sun that radiates into Space

Solar Prominences

Gases that shoot outward from the Sun's chromosphere

Constellations

Groups, or patterns, of stars, used by astronomers as reference points to locate other stars in the sky; Familiar ones include: Ursa Major (a.k.a. Great Bear/Big Bear), Ursa Minor (a.k.a. Little Bear).

Irregular Galaxy

Has no real structured appearance; most are in the early stages of life

The Chromosphere

Hydrogen gas causes this portion to be red; also found here are solar flares and solar prominences

Oscillating Universe Hypothesis

Hypothesis regarding the future of the Universe; The universe will expand and contract; Galaxies will move away from one another and will, in time, slow down and stop; Then a gradual moving toward each other will again activate an explosion - another big bang

Why does the position of a planet as seen from Earth change in relation to the background of the stars?

It is due to the fact that Earth and the other planets are physically moving in orbits around the Sun, so the planets' relative positions as seen from Earth (with respect to the fixed background stars) change as time goes on.

Main Difference Between the Sun and other Stars

Its proximity to Earth; very similar to other stars in comparing mass, light production, and size

Planets With No Moons

Mercury and Venus

Planets in Our Solar System

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Meteorites

Meteors that strike the Earth's surface; Example: Barringer Crater in Arizona is a huge meteor crater

Kuiper Belt

Name given to a vast population of more than 70,000 small bodies orbiting the Sun beyond Neptune; some with diameters larger than 100 km extending outwards from the orbit of Neptune to 50AU; exist mostly within a ring or belt surrounding the Sun; believed that the objects are primitive remnants of the earliest phases of the Solar System; a reservoir for Short-Period comets

Milky Way

Name of Earth's Galaxy; A spiral galaxy

Perihelion

Occurs around January 2nd of each year; when Earth is closest to the Sun; Northern winter is slightly warmer than Southern winter because the Earth is closest to the sun in January

Aphelion

Occurs around July 2nd of each year; when Earth is farthest from the Sun

Autumn Equinox

September 22; all locations on Earth experience 12 hours daylight and 12 hour darkness; Earth is south of the Sun

Brown Dwarfs

Starlike objects not massive enough to start fusion; failed stars; Not really stars because they are powered by gravitational contraction and not thermonuclear fusion.

Red Giants / Super Giants

Stars that are nearing the end of their life span; Hydrogen becomes exhausted in a small/average sized star, causing its core to collapse and temperature to rise; released heat causes nearby gases to heat, contract, carry out fusion, and produce helium

White Dwarf

The dying core of a giant star; A small, hot, dim star that is the leftover center of an old star

Gravitational Attraction

The force of attraction between all bodies in the universe

Sun

The main-sequence star at the center of Earth's Solar System, that generates solar energy by the process of nuclear fusion (converts hydrogen gas to helium gas); made up of 99.9% Hydrogen and Helium

Earth's Eccentricity

The slight deviation of the shape of the Earth's orbit around the Sun from the shape of a circle; has a small effect on Earth's climate

Total Lunar Eclipse

When Earth lines up between the moon and the sun; the moon moves into earth's shadow and appears dark in color; Moon is in Full Moon phase when this happens

Eclipse

When Earth, the moon, and the sun align so that light from one object is blocked