August 11
The Night Before the Storm
Sun Position
The Sun is in late Leo at about +14° declination. Northern Hemisphere observers are fully in the heart of summer darkness; Southern Hemisphere observers are approaching the last cold nights before spring.
Sky Highlight
The Perseid meteor shower reaches its peak on or around August 12-13. Tonight, rates are already near maximum, often 80-100 meteors per hour from dark northern sites after midnight. The radiant in Perseus climbs high in the northeast before dawn. Southern Hemisphere observers can look north for occasional streaks but rates are significantly lower.
Deep Sky Object
M15, the great globular cluster in Pegasus, begins to rise usefully in the late-night sky during August, offering a preview of the autumn sky to come. Roughly 33,600 light-years away, it is one of the densest globular clusters known and hosts a planetary nebula (Pease 1) visible only in large telescopes. Accessible from both hemispheres.
Featured Star
Deneb, the A2Ia blue-white supergiant in Cygnus, lies about 2,600 light-years away (nearly a hundred times farther than Vega) yet competes with it in apparent brightness, a testament to its extraordinary luminosity. The Milky Way at its Cygnus richness forms the backdrop behind it tonight.
Around This Date
- August 12, 1877Asaph Hall discovered Deimos, the outer moon of Mars, ending weeks of careful searching and confirming that Mars has natural satellites.
- August 20, 1977Voyager 2 launched on a trajectory designed to exploit a rare planetary alignment, allowing a single spacecraft to visit all four outer planets in one Grand Tour mission.
Deneb holds its brightness across 2,600 light-years; tonight the sky below it will be busy with Perseid meteors that burn out before traveling a single mile.