Download Patterns in the Night Sky Constellation: a grouping of stars, as

Patterns in the Night Sky
Constellation: a grouping of stars, as observed from Earth.
Celestial sphere: the imaginary sphere that rotates around Earth, onto which all celestial objects are projected.
Celestial navigation: the use of positions of stars to determine location and direction when travelling
Ecliptic: the path across the sky that the Sun, the Moon, the planets, and the zodiac constellations appear to
follow over the course of a year.
Retrograde motion: the apparent motion of an object in the sky usually a planet, from east to west, rather than in
its normal motion from west to east. (We can observe the retrograde motion of Mars, Jupiter, and Saturn with the
unaided eye.
Azimuth: the horizontal angular distance from north measured eastward along the horizon to a point directly
below a celestial body
Altitude: the angular height a celestial object appears to be above the horizon, measured vertically from the
horizon
Satellites: Artificial satellites help forecast weather, monitor agriculture, aid in telecommunication or navigation,
assist military activities, and explore the Universe.
Currently there are approximately 2,465 artificial satellites orbiting the Earth.
Types of Orbits:
The higher the satellite is, the longer the orbital period – the time it takes to circle Earth.
Low Earth Orbit Satellites:
Revolve around our planet at altitudes up to 2000km.
Polar orbit (200-900km): travels in a path that takes it over both the North Pole and the South Pole.
Allows the satellite to view all parts of Earth.
Used for military and Earth observation. Chart icebergs in Canada’s far Arctic oceans, monitor shifting patterns in
agriculture in Africa, and play an important role in natural disaster response in Asia.
Medium Earth Orbit Satellites:
Global positioning system (GPS) satellites travel in medium Earth orbits at about 11000km. They aid in
navigation by transmitting signals down to GPS receivers on the ground, providing them with precise
geographical coordinates of their location.
Geostationary Orbit Satellites:
Directly above the equator; appear motionless in the sky, which makes them useful for communications and other
commercial industries because they can be linked to antennas on Earth.
Communication industries use geostationary satellites for satellite broadcast television and radio.
SI Units
1km = 1*10^3m
1 AU = 1.5*10^11m
1 ly = 9.46*10^15m
Parallax: the apparent change in position of an object as viewed from two different locations that are not on a line
with the object.
The Characteristics of Stars:
Luminosity: the total amount of energy produced by a star per second
The luminosity of a star is measured by comparing it with the luminosity of the Sun, which is assigned a
luminosity of 1. Sirius, the brightest star in the night sky, has a luminosity of 22.
Apparent magnitude: the brightness of stars in the night sky as they appear from Earth.
Hipparchus classified the brightest stars in the night sky as “magnitude 1” stars, and the faintest stars as
“magnitude 6” stars.
Absolute magnitude: the brightness of stars as if they were all located 33 ly from Earth.
Star Colour and Temperature:
Solar Mass: a value used to describe the masses of galaxies and stars other than our Sun; equal to the mass of the
Sun (2*10^30kg)
Questions:
Earth’s revolution causes:
(a) stars to rise in the east and set in the west.
(b) stars to rise in the west and set in the east.
(c) the seasons.
In a solar eclipse:
(a) the moon is between the Earth & the Sun.
(b) the Earth is between the moon & the Sun.
(c) the Earth blocks the Sun.
Which of the following is a constellation?
(a) the Big Dipper.
(b) the Milky Way.
(c) Halley’s comet.
Which of the following is not an inner planet?
(a) Mars
(b) Saturn
(c) Earth
Which of the following is not an outer planet?
(a) Jupiter
(b) Venus
(c) Saturn
The order of stars from coolest to hottest is:
(a) blue, yellow, red.
(b) yellow, red, blue.
(c) red, yellow, blue.
7,9,1,5,8,6,4
What 3 factors affect the brightness of a star?
Distance of star from earth
Size of star
Temperature of star
What force is responsible for bringing together the
particles found in space?
(a) gravity
(b) terrestrial
(c) extra-terrestrial
Which of the following is not a common use of a
satellite?
(a) travel
(b) weather forecasting
(c) military
Satellites in a geosynchronous orbit are usually
located:
(a) above the South Pole.
(b) above the equator.
(c) above the North Pole.
When the speed of a low earth orbit satellite
increases
it:
(a) falls to earth.
(b) stays where it is.
(c) flies off into space.