Monday, November Warm-Up: Grade Content Frame 2. Astronomy Intro

Astronomy

1. ASTRONOMY is the scientific study of extraterrestrial objects and phenomena. Video

THE EARLY ASTRONOMERS In the year 1400, Ptolemy theorized that Earth was the center of the universe, and that the other planets and the sun revolved around the Earth. In 1543, Copernicus theorized that the sun was the center of the universe and that all of the planets revolved around the sun. Also in 1609, Kepler stated that the planets revolve around the sun in elliptical orbits. Kepler also theorized his laws of planetary motion that are still used today. In 1609, Galileo used the telescope to observe objects in space including craters and mountains on the moon and sunspots on the sun. In 1687, Newton showed that all objects attract each other due to gravity, explaining why one object orbits another. In 1924, Hubble proved that other galaxies existed beyond the Milky Way, and that the universe is much larger than our own galaxy Video

Different types of telescopes can detect different wavelengths to construct images, from visible light to radio to x-ray images. 13.

Constellations patterns of stars in the sky Modern Constellations- divides the sky into 88 constellations * Big Dipper * Little Dipper Circumpolar Constellations Constellations circle Polaris, they appear to move because the earth is in constant motion As the earth orbits the Sun, different constellations come into view while others disappear

The Location of the North Star Locating the North Star is easy if you follow this simple diagram. First, find the Big Dipper. Draw a straight line between the two Pointer Stars that are on the outside edge of the Big Dipper as shown, toward the Little Dipper. The North Star is located at the end of the handle of the Little Dipper. The North Star always points in the direction of True North. For this reason it has been used as an aid to navigation for many centuries. Another name for the North Star is Polaris. Pointer Stars and 19.

APPARENT MAGNITUDE Apparent Magnitude is how bright a star appears. Depends on how close the star is to us on Earth. Absolute Magnitude is the actual brightness of a star. Absolute Magnitude depends upon a stars size and temperature. When measuring the magnitude of a star, the lower the magnitude number, the brighter the star. ABSOLUTE MAGNITUDE ***If all stars were the same distance away, apparent and absolute magnitudes would be the same.***

APPARENT MAGNITUDE VS ABSOLUTE MAGNITUDE 26. What is the difference between apparent and absolute magnitude? Apparent magnitude is the brightness of a star as viewed form Earth, while Absolute magnitude is the true brightness of the star. 27. Which magnitude do we observe at night?Apparent Magnitude 28. Why does our Sun have the largest apparent magnitude? It is the closest star to us

Parallax is a star's apparent shift in position. Parallax can be used to determine the actual distance to a star by our change in position. Click for video Parallax

MEASURING DISTANCES IN SPACE 33. Distances in space are so large that astronomers use a special unit called a light-year. Light travels 300,000km in 1 second A light year is the distance that light travels in ONE year. A light-year measures distance NOT time

MEASURING DISTANCES IN SPACE 37. If a star located 65 light-years away from Earth stops giving off light energy at this very moment, how long will it be before we know? Explain. It will be 65 years after the star disappeared before we would even know it. The light takes that long to reach us. When using a telescope to observe stars, some say they are observing the past instead of the present. What does this mean? When you observe an object in space, you are really observing the way the object appeared at the time the light left the object. Depending upon how far the object is from Earth, you are looking at the object the way it appeared at some point in the past. 38.