Exploring Space Looking from Earth Telescopes are used to see objects that are far away. The largest telescopes are up to 300m wide There are 3 types Reflecting Refracting Radio Optical Telescopes Refracting and reflecting telescopes are both types of optical telescopes They use lenses and mirrors to produce magnified images Professional astronomers house the telescopes in observatories The Hubble Space Telescope was launched in 1990 in order to get better quality picture of the universe. Radio Telescopes All stars radiate energy throughout the electromagnetic spectrum Light, x-rays, radio waves, microwaves, etc… Radio telescopes study the radio waves A computer takes data about the radio waves and makes a map The largest radio telescope in the world is 300m wide Satellites Space exploration began in 1957 with the Soviet satellite Sputnik I Today thousands of artificial satellites orbit the Earth Space probes carry instruments to gather information and send it back to Earth. There have been several important probes sent out by the National Aeronautics and Space Administration (NASA) Mariner 2 Launched in August 1962 First successful planetary probe Verified high temperatures in Venus’ atmosphere Viking 1 Launched August 1975 Mapped Martian surface Searched for life on the surface Pioneer 10 Launched March 1972 First probe to encounter Jupiter Sent back photographs and data Voyager 2 probes were launched in 1977 Voyager 1 Voyager 2 Flew past Jupiter & Saturn Flew past Jupiter, Saturn, Uranus, and Neptune Sent back information from all the planets it visited Galileo Launched in 1989 Reached Jupiter in 1995 Sent a probe in to the atmosphere Returned data on composition, temperature, and pressure Also studied Jupiter’s moon’s, rings, and magnetic fields Race to the moon In 1961, President John F. Kennedy called for the US to put a person on the moon and began the space race. The race to the moon was undertaken in 3 projects Project Mercury Project Gemini Project Apollo Project Mercury Goal: To orbit a piloted spacecraft around the Earth and bring it back safely Significant Events May 5, 1961 – Alan Sheppard became the first US citizen in space 1962 – John Glenn became the first US citizen to orbit the Earth Project Gemini 2 astronauts in the same Gemini spacecraft orbited the Earth One team met and connected with another space craft in orbit. Ranger & Surveyor – Proved we could land on the moon Project Apollo Goal: to reach the moon July 20, 1969: Apollo 11 landed on the lunar surface Neil Armstrong became the first man to set foot on the moon. “One small step for man, one giant leap for mankind.” Beyond our Solar System Characteristics of Stars Color Temperature Brightness Mass Color and Temperature Color tells us temperature of a star Very hot stars = temperatures above 30,000 K are blue Stars between 5,000 K and 6,000 K appear Yellow Cooler stars under 5,000 K appear Red Stellar Mass Binary stars- 2 stars pulled together in orbit by the force of gravity They orbit each other around a center of mass If the center of mass is known than we can calculate mass of the stars Example- if the stars have equal mass the center of mass is exactly halfway between them Measuring Star Distance Shifting of a nearby star due to the orbital motion of Earth How is it done? Photograph a nearby star Photograph the same star 6 months later Calculate distance from star by the amount and angle of the shift Light Years Distances to stars are so large that we need a special unit to measure them 1 Light Year is the distance light travels in one years time 9.5 X 1012 Kilometers Or 9.5 trillion Kilometers Proxima Centauri is 4.3 light years away (9.5 trillion kilometers X 4.3) Stellar Brightness Magnitude = measure of star’s brightness Apparent magnitude – how bright a star appears from Earth Factors that effect apparent magnitude How big it is How hot it is How far away it is Absolute magnitude Actual brightness of a star 2 stars with the same absolute magnitude may not necessarily have the same apparent magnitude Stellar Evolution Stars start off as dark clouds of 92% hydrogen, 7% helium, < 1% heavier elements Gravity squeezes matter inward and the interior heats up Protostar- early phase where star is heating up (spans 1 million years) Star Birth When the core of the Protostar reaches 10 million K, pressure is so great that nuclear fusion occurs- a star is born Heat from fusion of hydrogen is released When balance is maintained from inward pressure (gravity) and outward pressure (heat) the Main-Sequence stage is reached Main-Sequence Stage Hydrogen fusion occurs for a few billion years Stars age at different rates Blue stars- burn so hot they deplete hydrogen quickly (few million years) Red/Yellow stars- burn cooler so their hydrogen lasts longer (our sun 10 billion years) Red Giant Stage Hydrogen depleted in core leaving a helium core Core loses outward heat pressure and begins to collapse As core contracts it grows hotter by converting gravitational energy into heat energy- this energy starts to fuse hydrogen in outer layers Red Giant Stage The heat energy expands stars outer layer resulting in a giant body hundreds to thousands of times larger than its main sequence size Previous events are all well documentedwhat happens next is based on theory Burnout and Death Stars eventually run out of fuel and collapse due to gravity Death of different size stars Low-mass stars Remain in main-sequence until fuel runs out and than collapse into white dwarf White dwarf- extremely dense remains of stars Black dwarf- a white dwarf that has cooled down Medium mass stars Reach giant phase fusing hydrogen and helium Then collapse from red giants to white dwarfs White dwarfs are extremely dense remains of stars Cast the outer layer creating an expanding cloud of red gas (called planetary nebula) Massive stars Have short life spans and die out with a brilliant explosion (supernova) During a supernova the outer layer of the star is ejected while the core collapses Star becomes a million times brighter than the prenova phase If one of the nearest stars to Earth went into supernova it would be brighter than our sun Black Holes During a supernova remnants of stars 3X the size of the sun collapse into small dense objects (Black Holes) These black holes have gravitational energy so strong that even light cannot escape their surface How do we find them? Look for the heat emitted as matter is being pulled in Galaxies Group of stars, dust, and gases held together by gravity Billions of stars in our galaxy- The Milky Way 100,000 light years across Spiral galaxy Types of Galaxies Spiral Great concentration of stars near the center Large galaxies containing billions of stars Elliptical Round to oval in shape Smaller galaxies Irregular Composed of mostly young stars Hubble’s Law Red shifts- Hubble observed that most galaxies have red shifts Red shifts show that light waves are being stretched This means that Earth and the source of the light waves are being moved away from each other Greater red shifts mean faster speeds Hubble’s Law Galaxies further away have greater red shifts and therefore are moving faster This discovery led to the Big Bang Theory The Universe is Expanding!!!! At one time the entire universe was confined to a dense, hot, supermassive ball. 13.7 billion years ago a violent explosion occurred hurling this material in all directions Evidence- 1) red shifts 2) cosmic radiation produced during the explosion What is the fate of our Universe? Expansion lasting forever as stars die out and the universe is filled with dense black dwarfs and black holes The Big Crunch- will gravity pull everything back into a high density, high energy mass as it was before the big bang?