Answers

ConceptChecks

ConceptCheck 2-1: No, Jupiter does not need to be one of the stars in the asterism that makes the outline of the bull’s body. Jupiter would only need to be within the somewhat rectangular boundary of the constellation of Taurus.

ConceptCheck 2-2: Earth rotates from west to east. As locations on Earth rotate from the dark, nighttime side of the planet into the bright, daytime side of the planet, the easternmost cities experience sunrise first. New York is the farthest east of the cities listed, so the sun rises there first.

ConceptCheck 2-3: The Sun would still only rise and set once each day (since that defines what a day is), but each year would have 3 times as many days (365 × 3 = 1095 days each year), and each day would be 3 times shorter.

ConceptCheck 2-4: The celestial equator is a projection, or an extension, of Earth’s equator out into the sky. In order for this imaginary line to pass directly overhead, one would need to be standing somewhere on Earth’s equator.

ConceptCheck 2-5: No, they would not; in this imaginary scenario, even near the north pole the Sun would rise and set every 12 hours all year long. Earth’s tilted axis means that observers near Earth’s north pole will experience six months when the Sun never rises (when it is tilted away from the Sun) and then six months when the Sun never sets (when it is tilted toward the Sun).

ConceptCheck 2-6: It takes one year. The Sun slowly moves through the sky a little each day, taking 365¼ days to return to the same place it was one year earlier.

ConceptCheck 2-7: To cast no shadow, the Sun must be directly overhead. As the Sun’s position on the celestial sphere slowly moves back and forth between the northern and southern solstice points over the course of a year, the noontime Sun will be directly overhead (and will cast no shadow) for an observer at Earth’s equator only twice each year, on the March and September equinoxes.

CalculationChecks

CalculationCheck 2-1: Earth rotates once in 24 hours, so when the stars of Cygnus rise in the east at sunset, they take about 12 hours to go from one side of the sky to the other. As a result, it takes about one half of that time, or 6 hours, for stars of Cygnus to move halfway across the sky. Thus, Cygnus will be highest in the sky around midnight.

CalculationCheck 2-2: The summer solstice occurs on about June 21 and the March equinox occurs about March 21, so there are about 9 months or 270 days between these two events.

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