# Astronomy Chapters 1-3

How many constellations are in the sky?
88
Why is looking in the sky like looking back in time?
Because the objects in space are so far from us that not even the speed of light can reach us in a timely manner.
How fast does light travel?
300,000 kilometers (186,000 miles) per second
The length of a light year is…
5,865,696,000,000 miles (9,460,800,000,000 kilometers) Method: 186,000 miles/second * 60 seconds/minute * 60 minutes/hour * 24 hours/day * 365 days/year = 5,865,696,000,000 miles/year
The length of an astronomical unit is…
150 million kilometers (93 million miles)
Write 137,000,000 in scientific notation
1.37 × 10⁸
Write .00622 in scientific notation
6.22 × 10⁻³
Multiply: 137,000,000 x .00622 ,and put it in scientific notation.
8.5214 × 10⁷
Order of the planets from closest to the sun to furthest away…Not including poor Pluto 🙁
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
What are five planets we can see in our sky from earth?
Mercury, Venus, Mars, Jupiter, and Saturn
Largest to smallest of the following; Milky Way, Earth, asteroid, universe?
Universe, Milky Way, Earth, Asteroid
What is the name for the apparent motion of the sky?
Diurnal Motion
The difference between rotation and revolution?
Rotation is when something spins on it’s axis. Revolution is when it moves around something.
The cause of the apparent motion of our sky?
The earth’s rotation on it’s axis.
The difference between sidereal day and solar day?
Solar day: One sunrise to the next, sun is in the same spot in the sky. Sidereal: Time it takes the sun to return back to the same location on the celestial sphere. The Sidereal day is 4 minutes shorter.
the direction the sun, stars, and planets rise and set?
They rise in the East, and set in the West
the length of a synodic month versus a sidereal month?
Synodic month: Time it takes the moon’s phases to go from full moon to full moon. 29 & 1/2 days. Sidereal month: Time it takes the moon to get back to the same location on the celestial sphere. 27 & 1/3 days
what does the magnitude of a star measure?
The brightness of a star
Define what the right ascension and declination are of an object on a sky chart
Right Ascension is the longitude on a star chart. Declination is the angular distance of a point north or south of the celestial equator, (latitude)
What causes seasons?
The tilt and revolution of the earth around the sun.
The shape of the Earth’s (and all planets) orbit is?
Circular
The reason seasons are different lengths? (If your answer is close, override)
Because of the wobble of the earth
what does the analemma show us about the sun at noon?
That’s it’s not always at it’s highest.
Name our latitude
39°
What’s the declination of the sun on an equinox, the winter solstice, and the summer solstice?
0°, -23.5°, +23.5°
What are the periods of rotation and revolution for the moon?
27 days of rotation, and 28 days of revolution
Why does the same side of the moon always face earth? (If your answer is close, override)
Because the moon spins once on its axis in precisely the same amount of time it takes to revolve around the Earth
Why do the phases of the moon occur? (If your answer is close, override)
As the bodies move, the Earth will block a part of the sun’s rays from hitting the moon, casting a shadow on it. The size of this shadow is what causes the various phases that are left visible to the eye.
What are the 2 major kinds of eclipses?
Lunar and Solar
Gravitational pull of the moon, and to a lesser extent the sun.
Why are there 2 high tidal bulges? (If your answer is close, override)
the moon’s gravity varies at different points on the earth’s surface that causes tidal bulges, there’s two because they occur on the closest point towards the moon, and the furthest.
Why do we have 2 high tides and 2 low tides per day?
The moon’s gravity (and to a lesser degree, the sun’s gravity) causes the water in the oceans to form a dome on the side of the earth facing the moon. And the same thing happens to the opposite side of the moon, due to physics. Low tides are in between these high tides.
how to measure the distance to the stars?
By using parallax
Whats the formula for parallax?
d=1/p (d= distance to star in parsecs) (P= parallax angle of star in arcseconds)
Why do more people see lunar eclipses than solar eclipses?
Because the moon is closer to us, Solar eclipses are rarer, are only visible on small segments of earth, and occur for a shorter period of time.
The significance of zodiac signs is that…
They fallow the earth’s orbit and the sun’s apparent path.
The significance of the ecliptic is that…
The ecliptic is the apparent path of the Sun on the celestial sphere, and is the basis for the ecliptic coordinate system
Evidence we revolve?
the stars appear at the same time in the night sky, and the sun goes to the same altitude
Evidence we rotate?
Time! Night-Day, ect…
Calculate the distance to an object with a parallax angle of .75
1.3 parsecs
Convert the distance of an object with a parallax angle of .75 to light years.
approx: 4.24 ly
Categories: Astronomy