Astronomy
Vocabulary:
• Celestial Objects (planets, moons, and asteroids)
• Earth
• Earth’s Tilt
• Gravitational force
• Instruments (Earth- and space-based)
• Lunar Eclipse
• Lunar phases
• Moon
• Orbital motions
• Orbits
• Pattern
• Revolution
• Rotation
• Seasons
• Solar Eclipse
• Solar energy
• Solar system
• Sun
Astronomy from Earth’s Perspective:
Before the invention of technology that enabled humans to leave earth’s perspective, astronomers relied solely on their observations of the heavens to make inferences about earth’s motions.
Earth’s Rotation:
Winter Summer
Polaris- Our North Star
Data Table
|Observer |1) Altitude of Polaris |2) Angle to the Equator |3) Latitude of the Observer |
|1 | | | |
|2 | | | |
|3 | | | |
|4 | | | |
Activity: Trace the Big Dipper and the Little Dipper below. Label both constellations and Polaris.
Apparent Motions Practice Questions:
How many degrees did the stars move from diagram 1 to diagram 2? ____________
How can you find Polaris? _________________________________________________________________
What hemisphere must you be in if you can see these constellations? Why? _________________________________________________________________
What direction must you be looking? ______________________________
Do the stars appear to move clockwise or counterclockwise? ___________________
What causes them to appear to move at all? __________________________________________________________________
Seasons:
Name the four seasons and their starting dates:
|Season |Starting date |
| | |
| | |
| | |
| | |
How many days are in each season on average? _______
What causes the seasons?
_________________________________________________
_________________________________________________
As earth revolves around the sun– the tilt of Earth’s axis does not change producing a cyclical change of seasons…. Earth’s axis is always tilted __________.
Is distance important to seasonal change? ________ because earth’s orbit is a
___________________________________
Earth is farthest away from the sun on ________ this is called _____________
Earth is closest on to the sun on ________ this is called _______________
What changes do we observe during seasons in NY?
1. ________________________ changes
-The sun is highest on June 21 (summer)
-The sun is lowest on Dec. 21 (winter
- _________________________ at our latitude.
2. ___________________________________ also change with the season.
-On the equinoxes, the sun always rise due east and sets due west.
-The rises and sets South of east and west in __________ and _____________.
-The Sun rises and sets North of East and West in ___________ and ____________.
3. __________________________( Duration of Insolation) changes with the season.
The tilt of the Earth on its axis is also responsible for the day and night length
- ___________ hours of day light: Shortest on Winter Solstice, Dec. 21
- ___________ hours of day light: Longest on Summer Solstice, June 21
-EQUINOX (MEANS EQUAL NIGHTS) =12 HOURS OF DAY AND 12 HOURS OF NIGHT
Important facts about the solstices and equinoxes in the Northern Hemisphere
|Summer Solstice |Winter Solstice |Both Equinoxes |
|1.June 21, longest day of the year. |1.Dec. 21, shortest day of the year. |1.Sept. 21 and March 21. |
|2.Sun at highest altitude at noon. |2.Sun at lowest altitude at noon. |2. Equal day/night 12 hrs of daylight, 12 hrs of |
|3.24 hrs of daylight at North Pole. |3.24 hrs. of darkness at North Pole. |night. |
|4.Direct sun ray at 23.5° north latitude. |4.Direct sun ray at 23.5° south latitude. |3.Direct sun ray at Equator. |
|5.Sun rise – NE, Sun set - NW |5.Sun rise – SE , Sun set – SW |4.Sun rise – E, Sun set – W. |
Practice Questions:
1) If Earth’s ax
is were tilted less than 23.5○, which seasonal average temperature change would occur in New York State?____________________________________
2) Which position of Earth represents the first day of summer in the Northern Hemisphere? _________
3) How many degrees will the Sun’s vertical rays shift on Earth’s surface as Earth
travels from position C to position D? ________________________
|Position |Season |Constellation Visible |
|A | | |
|B | | |
|C | | |
|D | | |
-----------------------
Systems & Models
(
Unit 5: Earth-Sun-Moon
Name:__________________ Class:_______ Date: ________
Note Packet #6
Science 8
Mrs. Gill-Klesaris
How does a man on the moon cut his hair… He Eclipse it!!!
P.S. I’m the MOON
Models of the Solar System
Based upon observations of the apparent motion of celestial objects.
Before our current understanding that the planets revolve around the sun, people actually believe that the sun and other planets revolved around earth.
___________________________
– The Sun is at the center, and the planets revolve around it
___________________________
– Earth is the center of the solar system, and all objects revolve around it.
-Used epicycles (small sub-orbits) to explain retrograde (backward) motion of planets
Celestial observations
The apparent daily motion of celestial objects (like stars) have enabled scientist to create theories about earth’s motions: rotation and revolution.
Rotation:
The apparent daily motions of the celestial objects in our sky are due to Earth’s Rotation or spin on its axis
How long is one rotation? ________
Rotation is responsible for:
-Day and Night (Local time)
-Rising and Setting of our Sun & Moon
-Movement of stars through the night time
sky
Axis– the imaginary line through Earth from the North Pole to the South Pole
Rotational Facts
• Earth’s axis is tilted 23.5 degrees
• Earth’s axis is always tilted in the same direction, this is called parallelism.
• Currently Earth’s axis points directly to the star Polaris (the North Star).
The earth rotates counter clockwise when looking from down at the North Pole
The earth rotates from West to East when looking at a side view of earth
How many degrees per hour does the earth rotate? 360 divided by 24= 15 so…
15 degrees per hour or 360 degrees per day
Example: Observer in New York
(43 degrees latitude)
1. The Altitude of Polaris is equal to your latitude: Because of the large distances and comparatively small size of Earth, the light rays reaching us from all stars, including the sun are essentially parallel. Imagine that we extended the Northern tip of Earth’s axis of rotation 430 light years into space. This imaginary line would hit the star Polaris (our North Star). We are quite fortunately to have a star directly in line with our axis because it enables us to use it for navigation purposes.
Rays from Polaris
Procedure A.
1. Estimate the angle between the light rays coming from Polaris and each observer’s horizon on the diagram below. The horizon is shown by the line drawn through the observer’s line of vision. Record this data in the data table below.
2. Measure the angles between each observer and the equator and record your data in the table below.
3. Can you infer the latitude of the observer at each location?
2. It’s Not Always easy to find Polaris even if you look up in the North Sky at the correct altitude.
Polaris is not especially bright; in fact, it is the dimmest star commonly used for celestial navigation. Therefore it is important to know how to locate Polaris in our night time sky! Polaris is the last star in the handle of the little Dipper (Constellation Ursa Minor). Unfortunately, the stars in Ursa Minor are also on the dimmer side of the luminosity (brightness) spectrum. Luckily the Big Dipper (Constellation Ursa Major) is easy to find and it is able to help us locate Polaris. The two stars that make up the outer side of the “cup” point directly to Polaris!
3. Polaris is a fixed Point in our sky and does not exhibit any apparent motion!
Our Earth rotates on its axis at a rate of 15Ú[?] axis at a rate of 15˚ per hour. Therefore all the stars in the sky appear to move from east to west at a rate of 15˚! (Best example: The Sun! It rises in the East and sets in the West). The only exception is Polaris and circumpolar stars that are close to Polaris, since it is directly above the North Pole. Since Polaris is so far away from us and is directly above our axis, it remains a fixed point in our night sky, despite the fact the Earth revolves around the sun and rotates on its axis. Label Polaris in the time lapse photograph on the right.
Earth’s Rotation:
Rotation is the spinning of Earth on its axis, which is an imaginary line drawn through the Earth from the North Pole to the South Pole.
We can make several observations that support the idea that earth is spinning.
Apparent Daily Motion
An apparent motion is a motion an object appears to make, it can be real or an illusion.
Celestial objects appear to move in the sky during the night.
This is due to the __________________________
Celestial Objects appear to move ______________, because Earth rotates 360° in ______ hours.
The apparent daily motions of stars changes when the observer’s _________________ on earth changes.
Using a time-lapse camera we can document this phenomenon. We call these images _________________
Stars are so far away they appear stationary (not moving) when you glance quickly at the night sky. Why do they have this pattern? _____________________
Apparent daily motion of the Big Dipper, a ___________________ constellation (never sets)
Revolution:
The apparent yearly change in position of all celestial objects is due to the Earth’s Revolution around the sun.
Period of revolution: the length of time for one orbit around the sun = 1 year
How many days are in 1 year ? ________
To account for the .26, Every leap year we add February 29 to our calendar to account for the four quarter days we accumulated over the last four years.
How many degrees does the earth travel in its orbit around the sun in one day?_____ How do we calculate this: 360 degrees divided by 365 days!
Revolution is responsible for:
-Change in the Sun’s Path across the sky
-Angle of Sunlight
-Seasons (combined with Earth’s tilt)
-Changing Seasonal Constellations
Label the seasons on the aerial views of earth…
Note the position of the shadow
Label perihelion and aphelion…
Apparent Solar Motion
Rotation cause Sun’s apparent daily path from sunrise to sunset has the shape of an arc moving l5° per hour. However, the sun’s arc changes both its position and its length with the seasons due to the earth’s Revolution.
The sun appears to move across the sky, like all celestial objects due to earth’s rotation. But sun’s apparent path in the sky varies by _______________ and _______________.
How does the location of the sun change throughout the year?
-No matter where you are on the globe, on the equinoxes, the sun will always rise due east and set due west. The path depends on your latitude.
-Changes in the altitude of the path and horizon position of sunrise and sunset are due to _______________________________
Your shadow!
-In NY, the noon sun will always be in the South Sky! So which way will your shadow fall? ________
-Your shadow always changes with the altitude of the sun and time of day!
-The length and direction of a shadow depends on the ____________________ and the observers ____________________. Both variables effect the sun’s altitude and the angle of insolation.
-Your shadow will always be opposite of the sun, if the sun is just rising in the east, your shadow will fall west. If the sun is high in altitude, your shadow is small, when it is low in altitude your shadow is long.
-Five different shadows, A', B', C', D', and E', are cast on a certain day by the post when the Sun is in positions A, B, C, D, and E, respectively.
Constellations:
Constellations are groupings of stars that make an imaginary image in the night sky. They have been named after mythological characters, people, animals and objects. In different parts of the world, people have made up different shapes out of the same groups of bright stars. It is like a game of connecting the dots. In the past constellations have became useful for navigating at night and for keeping track of the seasons.
Stars in constellations are often very far from one another but we see them in the same direction in the sky
Evidence of Earth’s Revolution around the Sun
-Seasonal Constellations: Because of the Sun’s annual motion, some constellations are visible at night only during certain seasons.
-Constellations are visible when the dark side of Earth (away from sun) faces toward the constellation.
-The 13 constellations the sun appears to travel through during the year
Directions:
Draw label the positions of the big dipper during the yearly cycle
The Moon
The __________ is Earth’s only natural satellite
It is estimated to be about ____________________ years old
Features
The Moon’s interior is thought to have _________, similar to earth
The Moon’s surface is covered with _________, caused by ________________ impacts.
The Moon’s Surface
Dark areas called _________ (from Latin mare, meaning sea). These are ancient lava flows.
Light areas are ___________________, which are mountain ranges made of lighter color rocks.
Moon Rocks
Rocks on the Moon are made of ______________ similar to those on Earth.
Rotation and Revolution
The Moon’s periods of rotation and revolution are both _________ days. The result is that the same side of the Moon always faces Earth (the near side).
However, it takes 29.5 days for the Moon to completely revolve around the Earth
Moon has to revolve for 2 more days to get back to the new moon phase
This occurs because the Earth is revolving around the Sun.
[pic]
Phases Of The Moon :
Moon Phases are apparent changes in shape due to the position of the Moon in its orbit.
Phase names:
New
Crescent
Quarter
Gibbous
Full
Waxing – becoming more visible
Waning – becoming less visible
What causes the phase of the moon? ________________________________________
Why does the moon rise later and later each day?
_________________________________________
How many hours is the moon visible each day? _____
The phase of the moon are a ____________ event.
Moon’s Effect on Tides
________ are the periodic rise and fall of the ocean surface
Tides are caused by the _________________________ of the Moon and the Sun on ocean water
High tide will occur when the __________ is overhead, as well as on the opposite side of the Earth.
How many tides a day? ______
Why are there not exactly 12 hours between tides? ___________________________
Phases and Tides
The alignment of the Moon with the Sun affect tides.
At the full and new moon phase, both are in line, causing a higher high tide and a lower low tide. This is called the ________________________.
At the quarter phases, the Sun and Moon work against each other, resulting in weaker tides, called _______________________.
Eclipses
________________________ occurs when the Sun’s light is blocked from either the Earth or the Moon.
We do NOT have solar and lunar eclipse every month because the orbit of the Earth and the Moon are along different planes, the moon orbit is tilted _________________.
Solar Eclipse
_________________ – (Earth goes into moon’s shadow) occurs when the Moon blocks the Sun’s rays from reaching Earth.
It occurs only at new moon phase.
Only a few people see it.
Moon blocks light to the Earth. Occur less often than lunar.
Lunar Eclipse
___________________ – (moon goes into earth’s shadow) occurs when the Earth blocks the Sun’s rays from reaching the Moon.
Only occurs at full moon phase.
Earth blocks light to the moon.
Moon must be in Umbra for a Total Lunar Eclipse.
Does not occur that often, moon orbit is tilted.
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