Astronomy 101 Review For Final Exam

1 AU stands for one astronomical unit, which is the average distance from Earth to the sun. It is the most commonly used unit to measure distances within our solar system. The other options, such as 1 million km, 1 million miles, 1 light year, and 1 billion km, do not accurately represent the average distance from Earth to the sun. Therefore, the correct answer is 1 AU.

A galaxy contains gas, dust, and stars, and a lot of dark matter. Galaxies are vast systems that consist of billions or even trillions of stars along with various amounts of gas and dust. These stars are held together by gravity and are surrounded by clouds of gas and dust, which can form new stars. Additionally, it is believed that a significant portion of a galaxy's mass is made up of dark matter, a mysterious substance that does not interact with light but exerts gravitational effects. Therefore, the correct answer is that a galaxy contains gas, dust, stars, and a lot of dark matter.

The correct answer is "all of the above" because the statement "The sun is a star" is true. The sun is indeed a star, specifically a G-type main-sequence star. Additionally, the statement "The sun is 1 AU from Earth" is also true. 1 AU (Astronomical Unit) is the average distance between the Earth and the Sun, which is about 93 million miles or 150 million kilometers. Lastly, the statement "The sun is more than 100 times the diameter of Earth" is also true. The diameter of the Earth is about 12,742 kilometers, while the diameter of the Sun is about 1.4 million kilometers, making it over 100 times larger.

In pre-Copernican astronomy, the prevailing belief was that the Earth was at the center of the universe. This geocentric model, supported by influential figures like Ptolemy, held that all celestial bodies, including the planets, revolved around the Earth. This view was based on observations that seemed to suggest that the Sun, Moon, and stars moved across the sky while the Earth remained stationary. It wasn't until the heliocentric model proposed by Copernicus in the 16th century that the understanding shifted, placing the Sun at the center of the solar system.

The given number, 2.9x10^7, is written in scientific notation. In scientific notation, a number is expressed as a product of a decimal number between 1 and 10 and a power of 10. In this case, 2.9 is the decimal number and 10^7 represents the power of 10. When the power of 10 is positive, it means that the decimal number is multiplied by 10 raised to that power. Since the power of 10 is 7, it means that 2.9 is multiplied by 10 seven times. Therefore, the number 2.9x10^7 is equal to 29 million.

A nanometer is a unit of length. It is commonly used in the field of nanotechnology to measure extremely small distances, such as the size of atoms or molecules. The prefix "nano" means one billionth, so a nanometer is equal to one billionth of a meter. This small unit of measurement is essential for accurately describing and manipulating objects at the nanoscale.

The Milky Way Galaxy contains about 100 billion stars. This is a well-known fact about our galaxy, as scientists have estimated the approximate number of stars it contains. The Milky Way is a spiral galaxy, and its vast number of stars contributes to its overall brightness and beauty when viewed from Earth. The estimation of 100 billion stars gives us a sense of the immense scale of our galaxy and the vastness of the universe.

Kepler's second law states that a planet should move at its greatest speed when it is closest to the sun. This is because as a planet orbits the sun, it sweeps out equal areas in equal time intervals. When a planet is closer to the sun, it covers a smaller distance in its orbit in the same amount of time compared to when it is farther away. Therefore, in order to cover the same area in the same time, the planet needs to move faster when it is closer to the sun.

The greatest inaccuracy in Copernicus' model of the solar system was that the planets traveled in circular orbits with uniform motion. Copernicus proposed that the planets moved in perfect circles at a constant speed, which was later proven to be incorrect. Kepler's laws of planetary motion showed that the planets actually move in elliptical orbits with varying speeds. This was a major breakthrough in understanding the true nature of the solar system.

A photon of blue light does not differ from a photon of red light in terms of speed. The speed of light in a vacuum is constant and does not depend on the color or wavelength of the light. Therefore, both blue and red photons travel at the same speed.

Saturn's average distance from the sun is 10 AU, which is the unit used to measure distances in the solar system, with 1 AU being the average distance between the Earth and the sun. The orbital period of a planet is the time it takes for the planet to complete one orbit around the sun. Since Saturn is farther from the sun than Earth, it takes a longer time to complete its orbit. Based on this information, it can be inferred that the approximate orbital period of Saturn is 32 years.

Photons of blue light have a greater energy than photons of red light. This is because the energy of a photon is directly proportional to its frequency, and blue light has a higher frequency than red light. Higher frequency means more energy per photon.

The statement "Gravity obeys an inverse square relation" means that the force due to gravity between two masses will decrease as the square of the distance between the two masses increases. This is because the gravitational force between two masses is inversely proportional to the square of the distance between them. As the distance increases, the force of gravity decreases exponentially. Therefore, the correct answer is that the force will decrease as the square of the distance between the two masses increases.

Long wavelength visible light will appear red in color to the average human eye. This is because the color of light that we perceive is determined by its wavelength. Red light has a longer wavelength than blue light, so when long wavelength visible light enters our eyes, it stimulates the red-sensitive cones in our retinas, resulting in the perception of the color red.

The correct answer describes Kepler's 3rd law of planetary motion, which states that the larger the orbit, the longer its orbital period. This means that planets that are farther away from the sun take longer to complete one orbit around it compared to planets that are closer. This law helps us understand the relationship between the size of a planet's orbit and the time it takes to complete that orbit.

The relationship between color and wavelength for light is that the wavelength increases from blue light to red light. This means that blue light has a shorter wavelength and red light has a longer wavelength.

Kepler's first law of planetary motion states that the orbit of a planet is an ellipse with the Sun at one of the two foci. This means that the distance between the planet and the Sun changes as the planet orbits the Sun. The planet is closer to the Sun at some points in its orbit and farther away at others. This explanation aligns with Kepler's first law and accurately describes the relationship between the planet and the Sun during its orbit.

By working backward from the current expansion rate, scientists can estimate the temperature and densities that existed at different times in the early universe. This is possible because the expansion rate is directly related to the conditions in the early universe. Therefore, by studying the current expansion rate, scientists can make informed estimates about the conditions that prevailed in the very early universe.

Infrared radiation has wavelengths that are longer than visible light.

The distance to a galaxy can be calculated using the equation v = H0 * d, where v is the redshift velocity, H0 is the Hubble constant, and d is the distance to the galaxy. Rearranging the equation to solve for d, we get d = v / H0. Plugging in the given values, we have d = 9,100 km/sec / 70 km/sec/Mpc = 130 Mpc. Therefore, the distance to the galaxy is 130 Mpc.

Prior to 10^-35 seconds after the Big Bang, the electroweak and strong forces were indistinguishable from each other. However, after this time, they started to behave differently from each other. This means that the forces that were once unified and combined into a single force began to separate and exhibit distinct behaviors. This event is known as the "freezing out" of the electroweak and strong forces, where they transitioned from being unified to behaving as separate forces.

Scientific notation is a useful tool in science because it simplifies the representation of both large and small numbers. By expressing numbers in the form of a coefficient multiplied by a power of ten, it becomes easier to write and comprehend extremely large or small values. This notation allows scientists to work with numbers that may involve many zeros, making calculations and comparisons more manageable. Therefore, the correct answer is that scientific notation makes it easy to write big or small numbers.

Gamma-rays, ultraviolet light, and X-rays all have wavelengths that are shorter than visible light. Gamma-rays have the shortest wavelengths and highest frequencies among the three, followed by X-rays and then ultraviolet light. These forms of electromagnetic radiation are all part of the electromagnetic spectrum, which ranges from radio waves with the longest wavelengths to gamma-rays with the shortest wavelengths. While infrared radiation is also part of the electromagnetic spectrum, its wavelengths are longer than visible light, so it does not fit the criteria of having shorter wavelengths.

The force due to gravity between two objects depends on the mass of each object and the distance between the two objects. The greater the mass of each object, the stronger the gravitational force between them. Similarly, the closer the objects are to each other, the stronger the gravitational force. The force of gravity is not affected by the distance of the objects from Earth or the speed of light.

Early organisms lacking skeletons and other hard structures are less likely to be fossilized compared to plants and animals with such structures. Fossils are typically formed when the remains of organisms are preserved in sedimentary layers over time. Organisms without hard structures are more likely to decompose or be destroyed before they can be fossilized, making their fossils more rare.

The neutral hydrogen atom consists of one proton and one electron. Protons are positively charged particles found in the nucleus of an atom, while electrons are negatively charged particles that orbit around the nucleus. In a neutral atom, the number of protons is equal to the number of electrons, resulting in a balanced charge. Therefore, the correct answer is one proton and one electron.

When Mars is located directly behind the Earth with respect to the Sun in its orbit, it means that Mars is in opposition. During opposition, Mars rises in the east at sunset, reaches its highest point in the sky at midnight, and sets in the west at sunrise. Therefore, it is at the midpoint in the sky between east and west at midnight.

During the GUT era, there were two forces that operated in the universe: gravity and a single force. This single force eventually evolved into the strong, weak, and electromagnetic forces that exist today.

The correct answer is "There are about 10^11 stars in the Milky Way Galaxy, but the mass of the Milky Way is about 10^12 times that of the Sun." This statement accurately represents the approximate number of stars in the Milky Way Galaxy and the mass ratio between the Milky Way and the Sun. It indicates that while there are a large number of stars in the Milky Way, the mass of the galaxy is significantly greater than that of the Sun.

The approximate orbital period of an object located 65 AU away from the sun is 524 years. This is because the orbital period of a planet or object is determined by its distance from the sun. The farther an object is from the sun, the longer it takes to complete one orbit. In this case, 65 AU is a significant distance from the sun, so the orbital period is much longer than the other options provided.

The period of the Milky Way to circle the Sun is about 225 million years. This means that it takes approximately 225 million years for our galaxy, the Milky Way, to complete one orbit around the Sun. This is a significant amount of time, highlighting the vastness and slow movements of celestial bodies.

Newton concluded that some force had to act on the moon because a force is needed to pull the moon away from straight-line motion. This is based on Newton's first law of motion, which states that an object at rest will stay at rest, and an object in motion will stay in motion in a straight line unless acted upon by an external force. Since the moon is not moving in a straight line, there must be a force acting on it to pull it away from straight-line motion.

The energy of a photon is inversely proportional to the wavelength of the light. This is because the energy of a photon is directly related to its frequency, and since frequency and wavelength are inversely proportional, the energy of a photon is also inversely proportional to its wavelength. As the wavelength increases, the energy of the photon decreases, and vice versa.