Tomorrow, I will check Science Journals! Bell Work for weeks 2, 3 and 4 Make sure that all your answers are highlighted! All our work from the last 3 weeks! Including your “adopt a constellation)

Bell Work Why do astronomers find it useful to retain the fiction of the celestial sphere to describe the sky? What vital piece of information is lost when we talk about their locations “on” the sky?

Bell Work J/K

Scale Scale Description 4 Through independent work beyond what was taught in class, you could: investigate the location of seasonal constellations in the local sky. predict location of constellations at future times. determine the celestial equator, latitude and position of the Pole Star for a given position on the Earth. determine the distances of stars in a given constellation to each other and to Earth. 3 You will be able to: describe and apply the coordinate system used to locate objects in the sky. distinguish the various methods of measuring astronomical distances and apply each in appropriate situations. 2 You will be able to: determine the meaning of symbols, key terms, and other astronomy specific words and phrases as they are used in context to relevant topics label diagrams with degree measurements describe how or why different units of measurement are needed for distances in space 1 You will be able to label diagrams with degree measurements list the different units of measurement needed to measure distances in space

Question of the day! Write these at the top of your paper. How does the Equatorial system compare to the horizontal system? Are there pros or cons to using one or the other? Vocab: arcminute, arcsecond, vernal equinox, declination, celestial equator Equatorial Coordinate System

lines that run east-west on Earth parallel to the equator are lines of latitude and when projected onto the sky, they become lines of declination. Like the latitude lines on Earth, declination (dec) is measured in degrees away from the celestial equator, positive degrees for objects north of the celestial equator and negative degrees for objects south of the celestial equator. lines that run north-south on Earth are lines of longitude and when projected onto the sky, they become lines of right ascension. the stars were used to measure time in the past, so right ascension (RA) is measured in terms of hours, minutes, and seconds and increases in an easterly direction.

Declination up and down (similar to altitude, but fixed) For instance, Vega's exact declination is +38° 47' 01” Declination (dec), which is measured in degrees (-90 for the south celestial pole, 0 for the celestial equator, and +90 for the north celestial pole). Partial degrees are usually described in terms of arcminutes (') and arcseconds (''). Think of declination as latitude Since ancient Babylonia, people have divided both degrees and hours into finer units by means of base-60 arithmetic. In 1° there are 60 arcminutes, written 60'. One arcminute contains 60 arcseconds, written 60". A good telescope in good sky conditions can resolve details about as fine as 1" on the surface of the celestial sphere. By comparison, 1" of latitude on Earth is about 101 feet. So if you had a telescope at the center of a transparent Earth, you could resolve details about as big as a house lot up on the surface. - See more

Right Ascension Right Ascension (RA), which is usually measured in hours, minutes, and seconds. Think of this as terrestrial longitude extended out into space, then measuring it in hours makes a bit more sense (time zones). You could just as easily measure it in degrees, too, where 1 hour is 15 degrees. RA is measured from the point where the sun crosses the celestial equator at the March equinox Vega's right ascension is 18h 36m 56.3s On Earth, 0° longitude has long been defined as a line engraved on a brass plate set in the floor under a position-measuring telescope at the Old Royal Observatory in Greenwich, England. In the sky, 0h ("zero hours") right ascension is RA is measured from the point where the sun crosses the celestial equator at the Vernal equinox

Summary Comparison Declination 1.What does it measure? 2.What are the units? 3.Where is the baseline? (the zero) 4.What would an example look like? 5.What does it relate to on Earth? Right Ascension

Work with your group to draw an accurate picture or sketch of the celestial sphere with both R.A. and Dec. represented

Bottom of page : in 2-3 sentences, answer the questions from the start of Tuesday and today’s activity using information from your notes. summarize

Tomorrow, I will check Science Journals! Bell Work for weeks 2, 3 and 4 Make sure that all your answers are highlighted! All our work from the last 3 weeks!