Studying Science Chapter 1

Astronomy: The Original Science Section 1 Vocabulary Astronomy Year Month Day

Introduction Seasonal cycles of the stars, planets, and the moon to mark the passage of time Best times of year to plant and harvest crops Observatories Study of the universe Led to first calendars

Our Modern Calendar Based on the observations of bodies in our solar system Time required for the Earth to orbit once around the sun Roughly the amount of time required for the moon to orbit around the Earth The time required for the Earth to rotate once on its axis

Who’s Who of Early Astronomy Helped people understand their place in the universe Oral histories Discovered with their eyes and minds Stars edge of the universe Ptolemy and Copernicus

Ptolemy: An Earth-Centered Universe 140 CE –book that combined all the ancient knowledge of astronomy that he could find Ptolemaic theory Earth was at the center of the universe and the other planets revolved around Earth (geocentric)

Copernicus: A Sun Centered Universe 1543-New theory that will eventually revolutionize astronomy Sun is at the center of the universe (heliocentric) Did not replace Plotemaic theory immediately Coperinican Revolution

Tycho Brahe: A Wealth of Data Late-1500’s-several large tools to make the most detailed astronomical observations Different geocentric model Sun and moon revolve around Earth Planets move around the sun

Johannes Kepler: Laws of Planetary Motion Brahe’s assistant –continued his work Did not agree with his theory 1609-all of the planets revolve around the sun in elliptical orbits and the sun is not in the exact center of the orbits. 3 laws of planetary motion

Galileo: Turning a Telescope to the Sky 1609-one of the first people to use a telescope to observe objects in space Craters and mountains on the Earth’s moon Four of Jupiter’s Moons Sunspots on the Sun Phases of Venus Not “Wandering Stars” but physical bodies

Isaac Newton: The Laws of Gravity 1687-all objects in the universe attract each other through gravitational force Force of gravity depends on the mass of the objects and the distance between them Explained why we travel around the sun

Modern Astronomy Edwin Hubble: Beyond the Edge of the Milky Way Two Milestones Invention of the Telescope Description of Gravity Before the 1920’s –thought the Milky Way (our galaxy) included every object in space 1924-proved that other galaxies existed beyond our galaxy Computers help process data and control the movement of telescopes

Telescopes Section 2 Vocabulary Telescope Refracting Telescope Reflecting Telescope Electromagnetic Spectrum

Introduction Standard tool Professional astronomers Amateur stargazers An instrument that gathers electromagnetic radiation from objects in space and concentrates it better for observation

Optical Telescopes Most common Helps to see so much more in the sky Study visible light from objects in the universe Helps to see so much more in the sky Collects visible light and focuses it to a focal point for closer observation The point where the rays of light that pass through the lens or that reflect from a mirror coverage

Optical Telescopes Simplest telescope has two lens 1. Objective Lens- collects light and forms an image at the back of the telescopes The bigger the lens The more light can gather 2. Second lens-located in the eyepiece of the telescope Magnifies the image produced by the objective lens

Refracting Vs. Reflecting Refracting Telescopes Reflecting Telescopes Telescopes that use lenses to gather and focus light Objective lens that bends light that passes through it and focuses the light to be magnified by an eyepiece Two Disadvantages Cannot be perfectly focused Size is limited due to the objective lens Telescope that uses a curved mirror to gather and focus light Light enters the telescope and is reflected from a large curved mirror to a flat mirror Flat mirror focuses the image and reflects the light to be magnified Advantages Mirrors can be very large Prevents light from entering the glass Focus all colors of light to the same focal point

Refracting Vs. Reflecting Refracting Telescopes Reflecting Telescopes

Very Large Reflecting Telescopes Several mirrors work together to collect light and focus it in the same area Hawaii Twin telescopes 36 hexagonal mirrors that work together Linking several mirrors-more light to be collected and focused in one spot

Optical Telescopes and the Atmosphere Light gathered by telescopes on the Earth is affected by the atmosphere Atmosphere Causes starlight to shimmer and blur due to the motion of the air above the telescopes Light pollution from large cities can make the sky look bright Places for telescopes Dry areas Mountaintops

Optical Telescopes in Space Hubble Space Telescope 2.4 meters across Can detect very faint objects in space

The Electromagnetic Spectrum Visible light Light that we can see Not the only form of radiation 1852-James Clerk Maxwell proved that visible light is part of the electromagnetic spectrum Made up of all of the wavelengths of electromagnetic radiation

Detecting Electromagnetic Radiation Each color of light is a different wavelength of electromagnetic radiation. We can see Red light-long wavelength Blue light-short wavelength Rest of electromagnetic spectrum-radio waves, microwaves, infrared light, etc. Atmosphere blocks most invisible radiation Can pass through-radio waves, microwaves, visible light, etc.

Nonoptical Telescopes To study invisible radiation Detect radiation that can not be seen by the human eye Each type of radiation reveals different clues about an object

Radio Telescopes Detect Radio waves Much larger than optical telescopes –radio waves are much longer than optical wavelengths Most can be detected day and night Does not have to be solid

Linking Radio Telescopes More detailed images Work like on large telescope Very Large Array 27 radio telescopes 30km

Nonoptical Telescopes in Space Most blocked by the earth’s atmosphere Put a lot of them in space Chandra X-Ray Observatory Detects X-Rays Much more sensitive

Mapping the Stars Section 3 Vocabulary Constellation Zenith Altitude Horizon Light-year

Patterns in the Sky Ancient cultures connected stars in patterns Named sections of the sky based on the patterns Sections of the sky that contain recognizable star patterns Help navigate and keep track of time Different civilization-different names Orion

Constellations Help Organize the Sky/Seasonal Changes A Region in the sky Shares a border with its neighbor Like states Every star or galaxy is located within 1 of 88 constellations As the Earth revolves around the sun, the apparent locations of the constellations change from season to season.

Finding Star in the Sky Astrolabe-can be used to describe the location of a star or planet-Used on relation to you Need to know three points of reference Zenith Altitude Horizon If you want to describe a star’s location in a relation to the Earth, you need to use the celestial sphere

The Path of Stars Across the Sky Most stars and planets rise and set throughout the night-apparent motion is caused by the Earth’s rotation Poles- the stars are circumpolar Stars that can be seen at all times of the year and all times of night They never set. Different areas of the universe are visible

The Size and Scale of the Universe Looking out a car window at trees Objects that are very far away do not appear to move at all Same for stars and planets 1500’s-Nicolaus Coperinicus noted that the planets appeared to move relative to each other but the stars did not Thought that the stars must be much farther away than the planets

Measuring Distance in Space Copernicus was correct. Light-Year-Unit of length equal to the distance that light travels in 1 year 9.46 trillion kilometers Farthest objects we can observe are more than 10 billion light-years away

The Doppler Effect Car Horn Doppler Effect-also occurs with light If a light source is moving quickly away from an observer, the light emitted looks redder than it normally does Redshift If a star is moving quickly toward an observer its light appears bluer than it normally does Blushift

An Expanding Universe Hubble-analyzed the light from galaxies and stars to study the general direction that objects in the universe are moving Light from all galaxies except our close neighbors is affected by redshift Rapidly moving away from each other All galaxies except our close neighbors are moving apart, the universe must be expanding