Astronomy

This map unfolds the entire night sky from sunset (at right) until sunrise (at left). Arrows and colored dots show motions and l ...

d TAURUS Pleiades Path of Comet PANSTARRS Sept 1 Oct 1 21 11 32 33 0.5° N E Comet PANSTARRS (C/2015 ER61) 30" September 17, 11:0 ...

5° LEO Mercury Venus Regulus Moon Mars September 18, 45 minutes before sunrise Looking east HYDRA 5° DELPHINUS CYGNUS SAGITTA AQ ...

44 ASTRONOMY • SEPTEMBER 2017 A: Finding something we’ve never seen before is hard, so naturally there are numerous parameters f ...

Vega Arcturus Jupiter Spica Regulus Sun MarsVenus Capella Procyon Betelgeuse Sirius Rigel W N E S WWW.ASTRONOMY.COM 45 overcome ...

O The wild and woolly menagerie of ghost worlds that once haunted the halls of astronomical history. by John Wenz Phantom planet ...

WWW.ASTRONOMY.COM 47 The grand fraud Thomas Jefferson Jackson See (1866–1962) was a lot of things. He was a brilliant astronomer ...

48 ASTRONOMY • SEPTEMBER 2017 “Astrometry, it turns out, is just tough to do from the ground because we’re looking through Earth ...

WWW.ASTRONOMY.COM 49 temperature and pressure. Objects above that threshold are stars. Brown dwarfs ini- tially produce heat by ...

50 ASTRONOMY • SEPTEMBER 2017 hen most Northern Hemisphere observers think of globu- lar clusters, they imagine a concentration ...

WWW.ASTRONOMY.COM 51 although it’s likely the dense clouds of Sagittarius hide a few dozen more. While the best and the brightes ...

52 ASTRONOMY • SEPTEMBER 2017 NGC 6934 The respectable globular cluster M30 resides in the con- stellation Capricornus. It’s eas ...

Winter As autumn skies give way to winter, the globulars become scarcer yet. Our first stop is M79 in Lepus the Hare, the target ...

54 ASTRONOMY • SEPTEMBER 2017 Partygoers and telescope hosts share a star-filled sky near Flagstaff, Arizona, during the city‘s ...

A star party and world-leading community are keeping the hometown of Lowell Observatory in the dark. by Christian Luginbuhl and ...

HPS LPS 10 9 8 7 6 5 4 3 2 1 0 PCALED NBALED 6000K White LED 2000K HPS LPS PCALED NBALED Incandescent White LED 100 90 80 70 60 ...

LED6000K LED2000K PCALED HPS NBALED LPS WWW.ASTRONOMY.COM 57 leading into town. The natural night sky — as an environmental qual ...

100 90 80 70 60 50 40 30 20 10 0 Unregulated Amount only Shielding onlySpectrum only Total 90% 25% 50% 70% Sky glow brightness 5 ...

WWW.ASTRONOMY.COM 59 lights are, and implementing “warmer” (that is, lower color temperature) solutions. Tucson, Arizona, for ex ...

60 ASTRONOMY • SEPTEMBER 2017 ON SATURDAY, APRIL 29, 2017, the inaugural “A m e r i c a ’s D a r k e s t S k y Star Party” was h ...