Astronomy 201 Flashcards
Chapters 1-5
From the position of Earth inside the Milky Way Galaxy, humans cannot see through to the far rim of the Galaxy with visible light because:
The space between the stars contains interstellar dust.
Which of the following is equal to 1 astronomical unit (AU)?
The average distance between Earth and the Sun
A reason why the International Date Line bends along the line?
To avoid cutting through groups of islands
X-rays coming from space can only be studied above Earth’s atmosphere because:
they are stopped by the large number of atoms in Earth’s atmosphere with which they interact.
Why do the speeds of the planets of the solar system in their orbits around the Sun vary?
Because of their elliptical orbits
Which of the following statements is true about electromagnetic waves?
They do not require a medium in which to travel.
Which of the following is a necessary condition for a celestial body to be deemed a planet?
It must orbit a star.
Which of the following is a limitation of Kepler’s laws?
They do not help us understand what forces of nature influence planetary motion.
Why do electrons get loose from the ground state, deep inside stars?
Because of the heat inside stars
The Local Group is part of a supercluster of galaxies, called the _____, which stretches over a distance of 110 million light-years.
Virgo Supercluster
For an ellipse, the ratio of the distance between the foci to the length of the major axis is called its _____.
Eccentricity
A difference between planets and stars?
Stars have the ability to consistently produce their own light, whereas planets lack this ability.
According to Niels Bohr, how do electrons remain in orbit around the nuclei?
By only following orbits of certain possible sizes
A reason for the appearance of dark bands in absorption spectra?
Absorption of light at certain frequencies by certain elements
Why was Kepler’s discovery of the elliptical shapes of the orbits of planets a decisive moment in the history of human thought?
Because it demonstrated that an acceptable cosmos could contain a more complex shape like an ellipse, instead of having only circles
The temporary apparent westward motion of a planet observed over the course of many nights as Earth passes between it and the Sun is called _____.
Retrograde motion
The ecliptic is the path _____.
The Sun appears to take around the celestial sphere
A reason atoms are not like a miniature solar system?
The typical atom is far emptier than our solar system out to Neptune.
The reason for Earth’s sky being fairly bright at twilight?
The scattering of sunlight by Earth’s atmosphere when the Sun is below the horizon
The difference between a solar day and a sidereal day?
Sidereal day is defined in terms of the rotation period of Earth with respect to the stars, whereas solar day is defined in terms of the rotation period of Earth with respect to the Sun.
What would occur as the eccentricity of an ellipse approaches one?
The ellipse would become flatter.
The speed needed to make a satellite orbit Earth without being drawn in by the planet’s gravity?
8 km/s
Dark matter
It cannot be directly observed, even with the help of instruments.
The similarity between all types of electromagnetic waves?
They all travel at the same speed in a vacuum.
The ancient Greeks made dedicated efforts to observe stellar parallax, the shift in the apparent direction of a star due to Earth’s orbital motion. However, they were unable to observe stellar paradox because of the:
Large distance between Earth and the stars.
Factors makes the existence of the asteroid belt between Mars and Jupiter possible?
The distance between the two planets
Why is the average Earth-Sun distance called an astronomical unit?
It was the most important measuring standard in the early days of astronomy.
Melanie travels to her friend’s hometown. She goes to the town square that lies at precisely 68 degrees north latitude. Which of the following points in the sky should Melanie look at if she wishes to spot the north celestial pole?
68 degrees above the northern horizon
Right ascension and declination are used by astronomers to
denote the positions of objects in the sky.
The general theory of relativity proposed by Albert Einstein led scientists to:
predict and observe black holes.
The slow and regular change in the direction in which Earth’s axis points is known as _____.
Precession
Each time zone covers _____ of longitude on average.
15 degrees
Ileana witnesses an eclipse for the first time in her life. At noon, she sees the sky getting visibly darker, animals getting really quiet, and she sees some stars for a brief period of time. Which type of eclipse did Ileana witness?
Total solar eclipse
A gas is heated and its temperature increases by 20 degrees Celsius. Which of the following is most likely to occur due to this increase in temperature?
The motion of the atoms will become more rapid.
Stars
All stars will die eventually.
Astronomical unit?
It is the average Earth-Sun distance.
Why do the planets, the Sun, and the Moon always remain within the zodiac?
Because their paths on the celestial sphere lie nearly in the same plane
Electromagnetic waves move through a vacuum by:
producing changing electric and magnetic fields.
Why did Pythagoras suggest that Earth should be a sphere?
Because he believed that the sphere is the perfect form
Why is the color of a star a rough indicator of its temperature?
Because many stars emit in the visible band
Why are certain celestial objects known as fixed stars?
Because they maintain fixed patterns among themselves through many generations
The path of an object through space is called its _____.
Orbit
Which of the following properties make microwaves effective in heating food?
They are absorbed by water molecules
Which of the following necessitated the adoption of standardized time zones?
The advent of faster means of transportation
Why does the Sun rise about four minutes later each day with respect to the stars?
Because of its motion on the ecliptic
The Republic of Maziland launched its first satellite into space. The satellite was launched into low Earth orbit with surgical precision. However, to the dismay of the scientists who worked on this project, the satellite became unstable and was pulled back into Earth’s atmosphere. Which of the following mostly likely caused this mishap?
Frictional drag generated by the swelling of Earth’s atmosphere
Magnetism is caused by _____.
The movement of charged particles
The distance between the Sun and Earth is 149.6 million km. This number is expressed in scientific notation as:
1.496 ×108 km.
To find their way around a multitude of stars in the sky, the ancients found groupings of stars that made some familiar geometric pattern or resembled something they knew. These groupings are known as _____.
constellations
Why do hydrogen atoms only produce dark lines at certain wavelengths in the visible absorption spectrum?
Because they only absorb photons with the exact energy needed to raise electrons to specific orbits
Gideon is traveling from Japan to the United States. When his flight reaches a point above the Pacific Ocean, the passengers are told by the flight crew to decrease the dates on their watches by one day. Which of the following did the airplane just cross?
The International Date Line
The application of Kepler’s first law of planetary motion?
Jupiter’s orbit around the Sun is elliptical.
Strongest argument for Earth not being a disk?
Earth’s shadow on the Moon during a lunar eclipse is always round.
The reason for the retrograde motion of planets observed from Earth?
A difference in orbital speeds between Earth and the other observed planets
A feature of Polaris that distinguishes it from other stars in the sky?
It is in a relatively stable position compared to other stars.
Reason for the speed of light being a natural unit of distance for astronomers?
Information about the universe comes to Earth almost exclusively through various forms of light.
Laws of nature?
The same laws apply everywhere in the universe.
The third quarter of the Moon’s phases when observed from Earth?
Half the Moon is illuminated at this time
The _____ is the nearest large spiral galaxy that is similar to the Milky Way Galaxy.
Andromeda galaxy