Final answer:
Stonehenge aligns with the sunset on the winter solstice, allowing the sun to shine directly through its structure. It served as an ancient observatory, marking the longest and shortest days of the year during summer and winter solstices.
Step-by-step explanation:
Stonehenge, located in England, is a prehistoric monument with significant astronomical alignments. It was constructed between 3000 and 1000 B.C., serving as an ancient astronomical observatory. During the summer solstice, on or about June 21, and the winter solstice, around December 21, Stonehenge aligns with the sun, marking the longest and shortest days of the year.
At the time of the winter solstice, the sunset aligns with the central axis of Stonehenge, and it is traditionally observed that the sun can be seen setting directly through the frame of the stones from the center of the monument. This contrasts with the equinox, occurring around March 21 and September 22, when the sun is perpendicular to Earth's axis, resulting in nearly equal day and night.
Therefore, the correct answer is that the sun could shine directly through the entire structure of Stonehenge during the winter solstice at sunset. Although there is a phenomenon on the northern stairs during the equinox, it's the Winter Solstice that uniquely aligns with the sunset through Stonehenge.