crescent moon

Until the 20th century, astronomers ignored the interiors of things. They had to. Telescopes only showed outermost layers.Scientists knew that a ball's "inside" constitutes virtually all its mass, but basic questions went unanswered: What, for example, lay below the dazzling solar surface? What mysteries might be found in the core of galaxies?

Wednesday August 13 around 5:15–5:30 a.m., early risers with a clear view of the eastern horizon can witness a rare celestial lineup: the crescent Moon alongside Venus—the dazzling Morning Star—with Jupiter shining above and Mercury low near the horizon. This nearly vertical arrangement of the three brightest night sky objects, plus elusive Mercury, happens only in late summer and early fall when the solar system’s plane aligns upright at dawn—making it well worth setting an early alarm.

Catch the crescent Moon hovering next to a bright star. It’s a famous one because it’s in the zodiac, in the constellation Gemini.

All this week we’re viewing crescent moons that grow fatter each evening. The crescent may be the Moon’s most fascinating phase.

The moon now has its strangest appearance. Several nights this week the moon will be in a lunar phase, the only one whose shape is not universally known. Everyone can identify a crescent or half or the full moon. But now we have a gibbous moon. That's the phase fatter than half but smaller than full.

This week on Strange Universe, Bob Berman discusses a triangle in the sky with two stars and the Crescent Moon.