The average speed of stars relative to the Sun in the solar neighborhood is about 20 km/s. Suppose you discover a star in the solar neighborhood that is moving relative to the Sun at a much higher speed, say 220 km/s
What kind of orbit does this star probably have around the Milky Way? In what part of the galaxy does it spend most of its time? Explain.
Since stars that are traveling along with us in the disk of the Milky Way move at a velocity relative to us of only about 20 km/sec, we would reason that a star observed to be moving relative to us at a velocity of 220 km/sec was not traveling with us in the disk but was part of some other component of the Milky Way, likely the halo. The orbits of halo stars are not concentrated in the flattened disk but are distributed more like a sphere. So a halo star flying through the disk would appear to us to have the rotational speed of the disk, namely 220 km/sec.
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Which statement about the length of a day is FALSE?
A) At the North Pole, the day lasts six months, then six months of night. B) At the equator, every day is twelve hours long, then twelve hours of night. C) For the United States, June 21st will be the longest day. D) The solar day is four minutes longer than the sidereal one. E) The sidereal day includes both the Earth's rotation and revolution around the Sun.
A student uses a plumb bob to verify that the doorjamb in a car is vertical. As the car pulls away from a stop, the student observes that the string now makes an angle ? with the doorjamb. Why does this happen?
What will be an ideal response?
In order to trap the starship Enterprise, the diabolical Klingons build a huge ideal solenoid 10 light-years long with a diameter of 2.0 million kilometers. Every kilometer of length of the solenoid contains 100 turns of wire
What magnetic field strength is produced near the center of the solenoid using a current of 2.00 kA? (?0 = 4? × 10-7 T ? m/A)
The point in Earth's orbit where Earth is farthest from the sun is known as
a. aphelion. b. perihelion. c. precession. d. the winter solstice e. a and d