October 2017 Discover

October 2017^ DISCOVER^65

CLOCKWISE FROM LEFT: AMIRREZA KAMKAR; NASA/ESA/H. BOND (STS

CI) AND M. BARSTOW (UNIVERSITY OF LEICESTER); ERNIE MASTROIANNI/DISCOVER; SOHO; NASA/ESA/H. TEPLITZ AND M. RAFELSKI (IPAC.CALTEC

H)/A. KOEKEMOER (STS

CI)/R. WINDHORST (ASU)/Z. LEVAY (STS

CI)

BRIGHTER DARKER

... -5 -4 -3 -2 -1 0 1 2 3 4 5 ...
Astronomers record brightness with a
number called magnitude. The lower
the number, the brighter the object.

THE SUN –26.7

SIRIUS, THE BRIGHTEST STAR

IN THE NIGHT SKY –1.5 VEGA, CHOSEN AS “ZERO POINT” 0.0

Vega

FAINTEST OBJECTS IN VISIBLE LIGHT WITH HUBBLE SPACE TELESCOPE 31.5