Academic/ELL Earth Science AGENDA

October 25, Wednesday:B Day

WARM-UPS:

1. Take out your constellation notes from last class, Friday, Oct 20

2. Read the information on rotation and revolution

OBJECTIVES:ASTRONOMY:Constellations

1. Use the information you read on rotation vs. revolution

a. Complete the “Rotation and Revolution” WORK SHEET 1 for practice

b. Complete the “Rotation and Revolution” WORK SHEETS 2 & 3

i. Write your NAME on Rotation and Revolution Worksheets 2 &3 and Mrs. Drewyer will collect it.

2. CONSTELLATIONS

a. Star Maps Activity

i. Work with your lab partners to complete the Star Maps Activity

ii. Use the information on “understanding Star Charts” to help you

iii. Mrs. Drewyer will collect your work at the end of class

HOMEWORK:

1. Be sure you have completed the H-R Diagram Activity AND TURNED it into me

2. Review the information on Rotation and Revolution

3. Review the information on seasonal vs. circumpolar constellations

4. Read the notes on “The Celestial Sphere” (sky MAP)

Seasonal vs Circumpolar Constellations

http://www.stargazersonline.org/episodes/1227.html

Circumpolar constellations revolve around the pole, and thus are visible all year long from that hemisphere (i.e. - constellations circumpolar to the north pole are visible all year long in the northern hemisphere). Some north circumpolar constellations include Ursa Major and Ursa Minor (the big and little dipper) and Cassiopeia. In the southern hemisphere, the star Eta Carina and the constellation Carina are circumpolar for the south pole. 

Seasonal constellations are not visible year round. As the Earth travels counterclockwise around the Sun each year, night looks out towards different parts of the Universe. At different seasons, different constellations cross the sky. Since there are 365 days in a year, and 360 degrees in a circle, the stars shift about one degree westward each night. 

Some examples for the northern hemisphere are: Orion and the Pleiades are famous "winter" constellations; a famous "summer asterism (part of a constellation) is the teapot asterism in the constellation Sagittarius.

· Short introduction video to navigation, star charts, vocabulary, and circumpolar constellations (Spanish subtitles)

· https://www.youtube.com/watch?v=jMLkLtBhEkU

· A Guide To Learn About The Constellations

· https://www.youtube.com/watch?v=uKXBtWHExwQ

Understanding Star Charts

To find constellations you’ll need a star chart, these give you a snapshot of what the night sky will look like at any one time and at any one location. The star chart above shows you how the night sky will look above most of the United States at 8 pm in late January. These maps may seem rather baffling and confusing at first but they’re actually very simple to use. To simplify matters the chart above only shows constellations but normally they will also indicate prominent stars, galaxies, nebulae and planets.

The first thing you may notice is that east and west seem to be the wrong way round, but if you imagine holding the chart above your head, which is how they are designed to be used, it becomes apparent this is not the case. The outer edge of the chart indicates the horizon, so the further the stars are from the edge the higher they will be in the sky.

The center of the chart shows the stars and constellations that will be directly overhead, so the map above shows you that the constellations of Auriga, Taurus and Perseus will be directly above you at that time.

To find your bearings it is helpful to find Polaris, the star which always points north. First find the famous Big Dipper, which is part of the constellation Ursa Major and visible all year in the Northern hemisphere, draw an imaginary line through the outer two stars of the Big Dipper’s bowl and you will come to Polaris, which is the brightest star in the constellation of Ursa Minor. In the Southern hemisphere it is helpful to find the Southern Cross, which always points south, this is done by drawing a line through the bright stars Alpha and Beta Centauri.

Once you have found your bearings you can start searching out constellations and the objects they contain. Using the chart above if you look south you’ll notice the constellation of Orion, perhaps the most recognizable constellation of them all. As well as the Orion nebula the constellation also contains the bright supergiant stars Betelgeuse and Rigel. Overhead and to the west you’ll find the Andromeda constellation which contains the Andromeda Galaxy, the most distant object that can be viewed with the naked eye. There are many other fascinating objects to look out for and a star chart will be essential in guiding you around the night sky.

Stars do not stay fixed in the night sky, as the Earth rotates they change position, as a result the night sky will look different at midnight from what it did several hours before or after. Most constellations are also seasonal, meaning that ones that are visible in winter may not be visible in summer and vice-versa, so sky charts usually come in seasonal versions. Constellations may also be drawn slightly differently on each chart and it’s also worth noting that there are separate charts for the Northern and Southern hemispheres.

Circumpolar Constellations

Circumpolar constellations are constellations that never set below the horizon when seen from a particular location on Earth.

They can be seen in the night sky throughout the year, while other constellations are seasonal, visible only at certain times of year.

The term circumpolar refers to constellations and stars that are circling the north and south celestial poles without ever dipping below the horizon. All circumpolar constellations are found near the celestial poles and, due to their proximity to the poles, they never disappear from view.

The five northern constellations visible from most locations north of the equator throughout the year are Cassiopeia, Cepheus, Draco, Ursa Major, and Ursa Minor.

Mapping Celestial Objects: The Celestial Sphere

Earth Maps:

Cartographers (mapmakers) and Geographers use Latitude and Longitude to designate

locations on maps.

· Latitude lines (parallels) divide the globe into the Northern and Southern Hemispheres

· Latitude lines are drawn from East to West (0 - 90 N, S)

· Longitude lines (meridians) divide the globe into the Eastern and Western Hemispheres

· Longitude lines are drawn from North to South (0 - 180)

· Latitude and Longitude Lines are drawn on MAPS.

· Lines of Latitude and Longitude are measured in Degrees, Minutes, and Seconds)

Celestial Maps:

Astronomers use Declination and Right Ascension to designate locations on the Celestial

Sphere.

· Declination corresponds to Lines of Latitude

· 0 Declination corresponds to the Celestial Equator

· Points above the Celestial Equator are designated by '+'

· Points below the Celestial Equator are designated by '-'

· Values for Declination range from 0 to 90 (0 to +90, and 0 to -90)

· Right Ascension corresponds to Lines of Longitude

· Right Ascension is measured in HOURS and MINUTES

· 0 hours Right Ascension = where the sun crosses the celestial equator on the Vernal Equinox

· The values for Right Ascension are measured Eastward from 0 hours to 24 hours (24 hours = 360)

· These lines are drawn on the CELESTIAL SPHERE to designate locations of celestial objects (planets, stars, comets, moons, etc.)

Reference Points on the Celestial Sphere:

Celestial Equator: The projection of Earth's Equator on the Celestial Sphere (0)

North Celestial Pole: The projection of Earth's North Pole on the Celestial Sphere

(+90)

South Celestial Pole: The projection of Earth's South Pole on the Celestial Sphere

(-90)

Ecliptic: The Apparent Path of the Sun on the Celestial Sphere – the Zodiac constellations are located along the ecliptic (visually). There are now 13 zodiac constellations – with the addition of Ophiuchus. (This actually was there but was thrown out - 12 instead of 13 constellations -to more closely match the Roman calendar).

Circumpolar star simulation

http://earthsciencenhs.wikispaces.com/Stars+and+Constellations

The TILT of Earth on its axis is 23.5 °. The latitude that corresponds to the tilt is the Tropic of CANCER in the Northern Hemisphere (23.5° N) and the Tropic of CAPRICORN in the Southern Hemisphere (23.5° S)

REVIEW:

Rotation of the Earth on its AXIS causes _________ and _________

Revolution of the Earth around the SUN causes ________________

NAME:

Rotation vs Revolution Work sheet 1