Astronomy Chapter 1 Charting the Universe
Obj.#1 What is Astronomy? Astronomy is the study of the Universe The universe is the total of all space, time, matter, and energy The universe is made up of galaxies
Our Galaxy …The Milky Way
Galaxy NGC 300
Light year- distance traveled by liht in one year Light years are used to measure the universe The speed of light is 186,000 per second
Obj. #2 What is a constellation? Humans made patterns of stars that they saw in the sky These patterns are by chance. Humans can see around 6,000 stars with the naked eye
The Big Dipper
Obj. 3 Describe the Celestial Sphere The celestial sphere is an imaginary sphere that surrounds Earth. The stars and planets appear to be attached to the sphere It is used to help locate stars and planets
Important parts of the celestial sphere North Celestial pole- directly over the north pole South Celestial pole- directly over the south pole Celestial equator- circle half way between the North and South Celestial Sphere
Celestial Sphere
Declination- angular degrees above and below the equator- ( similar to latitude line on an Earth globe) Vernal Equinox is the 0 point on the celestial equator line Right Ascension- measured in hours and measures distances eastward of the Vernal Equinox
Declination lines
Lines of Ascension
Zenith- Where ever you are located…the point directly over your head on the celestial sphere
Zenith
Obj. 4: Distinguish between a Solar Day and a Sidereal Day Solar Day- basic time unit of 24 hours that it takes the Earth to rotate on its axis Sidereal Day- a day measured with respect to the stars. It is 23 hours and 56 minutes
Solar and Sidereal Day
Obj. #5: Explain what causes seasonal changes Elliptic Plane is the Earth’s orbit around the Sun Summer Solstice- the point where the Earth’s North pole is pointed at the Sun Occurs on June 21…longest day of the year
Winter Solstice- shortest day of the year South pole faces the Sun Equinoxes- when the light during the day and night are equal
Reason for the Seasons The Earth is tilted at 23.5 degrees all year long. Sunlight strikes the Earth’s surface at different angles during the year causing the changes in the season. We are not closer to the sun in the summer!!!
Reason for the Seasons
Obj. 6: Describe precession Precession is the change of the Earth’s cycle over time. One complete cycle takes 26,000 years to complete
Objective 7: Explain the Phases of the Moon The Sun always lights half of the moon. What part of that light we see from Earth depends on where the Moon is located as it travels around Earth.
Phases of the Moon 1.New Moon- the near side of the moon faces away from the sun making observers on Earth see the dark side. 2.Waxing Crescent- this means that the right side is brighter and appears to be making a crescent.
New Moon
Waxing Crescent
3.Quarter Moon- at this stage one would be one-half of the moon. Light is on the right. 4.Waxing Gibbous Moon- when the quarter moon begins to grow…almost full 5.Full moon-occurs two weeks after new moon.
Quarter Moon
Waxing Gibbous
Full Moon
6.Waning Gibbous- when the light begins to shrink. 7.Third quarter moon- moon with ½ light on the left side 8.Waning Crecent- has a crescent on the left side.
Waning Gibbous Moon
3 rd Quarter Moon
Phases of the Moon
Obj. # 8 Describe a lunar and solar eclipse Lunar eclipse-occurs when the Earth is directly between the Sun and Moon. Earth’s shadow falls on the moon. Solar eclipse- occurs when the moon is directly between the Sun and the Earth. The Moon blocks sunlight from hitting Earth.
Lunar Eclipse
Solar Eclipse