Astronomy Exam 1

Newton's 3 Laws of Motion are

- A body continues at rest in a straight line unless acted upon by an external force - A body's change of motion Is proportional to the force acting on it, and is in the direction of the force. - When one body exerts a force on a second body, the second body exerts an equal and opposite force back on the first body.

Kepler's 3 laws of planetary motion are

- The orbits of the planets around the sun are ellipses with the sun as one of the foci - The speed of a planet in orbit varies according to its position, covering equal areas in equal intervals - The orbital period squared is proportional to the semi-major axis cubed. The farther away from the sun a planet is, the longer it takes to orbit the sun

Because Earth rotates on its axis, the

- sun appears to rise in the east and set in the west. -stars appear to rise in the east and set in the west. -lane of motion of a pendulum changes.

If two stars differ by five magnitudes, the intensity ratio of the two stars is

100

What is the celestial sphere

A large imaginary crystalline sphere that surrounds the Earth. Ancient Greeks thought of the celestial sphere but now it is only used as a model in astronomy.

Who formulated the special and general theories of relativity?

Albert Einstein

What is the difference between an asterism and a constellation?

An asterism is a named sky patter that is not on the official list of constellations. A constellation is a grouping of stars that cultures have assigned a meaning to.

The instrument that can record the image of a faint object in the least amount of observing time is the

charge-coupled device (CCD).

According to Kepler, the orbits of the planets are

ellipses with the sun at the center.

According to the special theory of relativity, the relationship between matter and energy can be expressed as

E = mc2

The speed of light is the same for all observers, and the laws of physics are the same for all observers in uniform motion. These two statements are fundamental postulates of

Einstein's special relativity.

What is a precession of the Earth?

Precession is caused when the Earth Is orbiting, it wobbles due to gravitational pulls from the moon and the sun. This wobble causes the celestial poles to slowly move their positions against the background stars of the Celestial Sphere

The statement that astronauts on the Moon are weightless is

false because the Moon exerts a gravitational force on their bodies.

How has the magnitude scale of Hipparchus been updated for use by today's astronomers?

Modern astronomers have updated the magnitude scale model to be more accurate now. It includes negative number for bright objects like the sun and high numbers for extremely faint objects only detectable with space-based telescopes.

According to general relativity, space-time, in the presence of matter

is curved

If you were on the lunar surface during a full moon, new moon, first quarter, and waxing crescent as viewed from Earth, Earth's "phase" would be

New Moon: phase on Earth is full moon. Full Moon: phase on Earth Is new moon First Quarter: the phase on Earth is third quarter. Waxing Crescent: phase on Earth is gibeous

In Earth's northern latitudes, summer is warmer than winter because summer days are

longer than winter days and sunlight strikes the ground at an angle and spreads out.

spring tides occur at

new moon and full moon

In the penumbra region of Earth's shadow during a solar eclipse, an observer would

See a partial eclipse with the moon blocking only a portion of the sun's surface.

Where on the Earth would you have to be to be able to see Polaris at the south point on your horizon?

The North Pole

What is the astronomical unit and when is it used?

The average distance from the Earth to the sun. It is used to express the distance to things in the solar system

What is a light-year and how is it used?

The distance the light travels between the stars in one year. Used to express the distance between stars in a number that we can imagine.

What is the celestial equator

The imaginary line around the sky directly above Earth's equator.

What causes the phases of the moon?

The moon goes through different phases because it rotates once a month around the earth. The phases we see are the suns light shining on a paricular part of the moon.

Why do we not see solar and lunar eclipses each month?

The moon's orbit is tilted by about 5 degrees to the ecliptic. The only time an eclipse can happen is when the sun is located near one of the two points where the moons orbit crosses the ecliptic.

Imagine a heavy anvil and a feather were dropped from the top of a mountain on the moon. What will happen?

They will impact the lunar surface at the same time

Which types of electromagnetic radiation cannot penetrate Earth's atmosphere?

X ray, infrared, ultraviolet, gamma ray

What is an epicycle?

a circle whose center is located on the circumference of another circle.

What is a paradigm?

a commonly accepted set of scientific ideas and assumptions.

What is a photon?

a particle of light

A "particle of light" refers to

a photon

What is a theory?

a system of rules and principles that can be applied to a wide variety of circumstances, but that is NOT universally accepted

What is active optics and adaptive optics?

active optics controls the shape of a telescope mirror to correct sagging. Adaptive optics attempts to reduce the blurring in the image caused by earth's atmosphere.

If a moon crosses in front of the sun while the moon is at apogee.

an annular eclipse occurs.

What does a spectrograph do?

analyzes light by spreading it out according to wavelength

Newton's law of universal gravitation states that the force of gravity between two objects is

proportional to the square of the distances between the objects.

In its orbit around the sun, a planet's speed is

slowest at aphelion.

As observed from Earth, the planets

speed up, slow down, stop, and move backward with respect to the background star

Which of the following are not members of the solar system?

stars

Galileo's telescopic discovery of moons orbiting Jupiter was important because it showed

that the universe could contain centers of motion other than Earth.

Spring begins in the northern hemisphere on the vernal equinox, which occurs when

the Sun crosses the celestial equator going northward.

The apparent visual magnitude scale refers to

the brightness of stars that are only visible with the naked eye.

What is the scientific notation?

the method by which large numbers are written with powers of 10. Scientists use to make it easy to write big numbers

Perihelion Is

the point in the orbit of a planet which it is closest to the sun.

Aphelion Is

the point in the orbit of a planet which it is furthest from the sun.

time dilation refers to

the slowing of time of moving clock as measured by an observer considered to be at rest.

What is astronomy?

the study of the universe as a whole

The seasons on Earth depend on the

tilt of Earth's rotation axis with respect to the ecliptic.

What is retrograde motion? How does it happen

when the Earth and another planet are side by side and lined up with the sun, the planet farther away from the sun appears to slow down and reverse its direction.