A Clear Voice for Science
Diana asks, “Why is the waxing moon always so high in the evening sky in late winter and early spring?” In a nutshell, Diana, it is because the ecliptic arcs high across the evening sky right now. The ecliptic is the Earth’s orbital plane projected onto stellar sphere, or the dome of sky. The ecliptic is often shown on sky charts because the moon and planets are found on or near the ecliptic.
If you are familiar with the constellation Orion, you will always know when the ecliptic soars highest in the northern hemisphere sky. The ecliptic arcs from east to west, and swings way over Orion. Whenever Orion appears in the southern sky, the ecliptic stands highest in the sky.
More specifically, the ecliptic is most inclined to the horizon when the summer solstice point resides on the meridian (or due south). Orion’s brilliant ruddy star Betelgeuse and the summer solstice point cross the meridian at nearly the same time this evening, at about 8 p.m. local time. Betelgeuse (and the summer solstice point) return to the meridian about 4 minutes earlier daily, or 2 hours earlier with every passing month.
Ecliptic highest in sky:
Sunset on the spring equinox
Noon on the summer solstice
Sunrise on the autumn equinox
Midnight on the winter solstice,
Written by Bruce McClure
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