Midterm Flashcards
What is a constellation? Why do we see different constellations throughout the year?
A constellation is one of the 88 sectors into which we divide the sky for scientific reference (ex big dipper).
The constellations you see at night depends on the time of year as Earth is in different spots throughout its orbit.
What is an Asterism?
A pattern of stars ewhich is within a constellation or may span several constellations
What is an Eclipse
An eclisp le of the sun by the moon, caused by the passage of the moon in front of the sun. Solar Eclipses can only occur at the time of the new moon.
why don’t we have eclipses every month
the orbit of the moon is tilted relative to the orbit of the Earth around the sun, so the moon often passes below or above Earth. At those times, it does not cross the line between the sun and the Earth, and therefore does not create a solar eclipse.
reasons for the seasons, debunking the misconceptions of earth/sun distances and the geometry of the seasons
The Earth’s tilt and elliptical orbit around the sun cause seasons, not the Earth’s distance from the sun. The Earth’s axis is tilted 23.5 degrees relative to the plane of orbit around the sun, and as the Earth orbits, the axis points to the same fixed location in space. When the North Pole tilts toward the sun, it’s summer in the Northern Hemisphere, and when the South Pole tilts toward the sun, it’s winter in the Northern Hemisphere
Explain tides
At the surface of Earth, the gravitational force of the Moon is about 2.2 times greater than that of the Sun. The tide-producing action of the Moon arises from the variations in its gravitational field over the surface of Earth as compared with its strength at Earth’s center. The effect is that the water tends to accumulate on the parts of Earth’s surface directly toward and directly opposite the Moon and to be depleted elsewhere. The regions of accumulation move over the surface as the position of the Moon varies relative to Earth, mainly because of Earth’s rotation but also because of the Moon’s orbital motion around Earth. There are approximately two high and two low tides per day at any given place, but they occur at times that change from day to day
How to use Keplers third law equation?
The equation for Kepler’s Third Law is P² = a³, so the period of a planet’s orbit (P) squared is equal to the size semi-major axis of the orbit (a) cubed when it is expressed in astronomical units.
What is an ellipses?
In astronomy, an ellipse is an oval shape with two foci, a major axis, a minor axis, and a center. The major axis is the longer axis, and the minor axis is the shorter axis. The center of an ellipse is the midpoint of both the major and minor axes.
Ellipses parts
Major axis: The longest axis, which goes through the center from one end to the other. It contains both foci and is the longest line of mirror symmetry that can be drawn through an ellipse.
Minor axis: The shortest axis, which crosses through the center at the narrowest part. It is the perpendicular bisector (a line that divides another line into two parts) of the major axis.
Semi-major axis: Half of the major axis, and the average distance between the sun and a planet.
Vertices: The endpoints of the major axis.
Co-vertices: The endpoints of the minor axis.
Apse points: The extreme points on the major axis of the orbit.
Periapsis: The point closest to the attracting body.
Apoapsis: The farthest point
Kepler’s explanation for why the planets behave as they do
The closer a planet is to the Sun, the stronger the Sun’s gravitational pull on it, and the faster the planet moves. The farther it is from the Sun, the weaker the Sun’s gravitational pull, and the slower it moves in its orbit
Keplers first law
Kepler’s First Law: each planet’s orbit about the Sun is an ellipse. The Sun’s center is always located at one focus of the orbital ellipse. The Sun is at one focus. The planet follows the ellipse in its orbit, meaning that the planet to Sun distance is constantly changing as the planet goes around its orbit.
Keplers second law
Basically, that planets do not move with constant speed along their orbits. Rather, their speed varies so that the line joining the centers of the Sun and the planet sweeps out equal parts of an area in equal times. The point of nearest approach of the planet to the Sun is termed perihelion. The point of greatest separation is aphelion, hence by Kepler’s Second Law, a planet is moving fastest when it is at perihelion and slowest at aphelion.
Keplers third law
the squares of the orbital periods of the planets are directly proportional to the cubes of the semi-major axes of their orbits. Kepler’s Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit.
How does mass and distance affect gravity?
Gravity is affected by the size of objects and the distance between objects. A measure of the amount of matter in an object is mass. An object with a greater mass falls faster than an object with a smaller mass. When the distance between two objects increases, the force of gravity decreases. inverse square
Issac Newtons three laws of gravity
1.An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.
2.The acceleration of an object depends on the mass of the object and the amount of force applied.
3.Whenever one object exerts a force on another object, the second object exerts an equal and opposite on the first.
