Skywatchers are calling it the biggest sky day in years. Before dawn Wednesday, six planets strung themselves across the pre-sunrise sky, and after dark the Perseid meteor shower reaches its annual peak — bracketing today's total solar eclipse, covered separately, with two more reasons to look up.
Mercury, Mars, Jupiter, Saturn, Uranus and Neptune arced from the eastern horizon toward the southwest for Northern Hemisphere viewers Wednesday morning, according to Star Walk's viewing guide. The window ran roughly 30 to 60 minutes before local sunrise — about 5:18 to 5:34 a.m. in New York. Mars and Saturn were the easiest targets for the naked eye; Mercury sat low and required a clear, unobstructed horizon; Jupiter hung even lower than Mercury; Uranus needed binoculars; and Neptune was visible only through a telescope. Six-planet lineups are uncommon because they require the planets' distinct orbital periods to briefly bunch on the same side of the sun as seen from Earth.
The Perseids take over after sunset. The shower, produced by debris shed from comet Swift-Tuttle, peaks overnight into Thursday, with its radiant point in the constellation Perseus climbing highest after midnight. A new moon Wednesday strips away moonlight interference, giving what the Royal Observatory Greenwich and other forecasters describe as some of the darkest, clearest Perseid conditions in years. Under those dark-sky conditions, observers can expect to see roughly 50 to 100 meteors an hour, though the theoretical zenithal hourly rate — a measure assuming a perfectly dark sky with the radiant directly overhead — runs higher.
Astronomers recommend skipping telescopes and binoculars for the meteors themselves: the widest possible view of the sky, away from city lights, with eyes given 20 to 30 minutes to adjust to the dark, works best. No special equipment is needed for the planet alignment either, aside from binoculars for Uranus and a telescope for Neptune. Forecasters note the alignment will remain loosely visible for several mornings before and after Wednesday, but the Perseids' peak window is narrower, favoring tonight and tomorrow night before the rate tapers off through the rest of August.
