Astronomy

WWW.ASTRONOMY.COM 21 Einstein’s relativity replaced Newton’s gravity. Now observations of black holes might test the limits of A ...

Sun Mercury at perihelion Pre cess ion Me rcu ry’s (^) orbi t 22 ASTRONOMY • JULY 2018 N FEBRUARY 11, 2016, two teams of scienti ...

Sun White dwarf Neutron star Black hole WWW.ASTRONOMY.COM 23 be accelerating are still controversial. “Is that because we don’t ...

24 ASTRONOMY • JULY 2018 comes closest to the Sun, called peri- helion, advances about 2° per century. Relativity accounts for t ...

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26 ASTRONOMY • JULY 2018 space. Einstein’s theory says it doesn’t matter what that mass is, but astrono- mers think nature makes ...

Supermassive (4 million solar masses) 15 million miles (24 million km) 4.7 Earths across Stellar mass (10 solar masses) 37 miles ...

Detector End station Mid station Corner station 1.24 miles (2 km) 1.24 miles (2 km) Mirrored test mass Mirrored test mass Mirror ...

N E 0.1" 1995–2017 S2 S38 S102 S5 S16 S19 S20 WWW.ASTRONOMY.COM 29 measurement of the underlying theory of gravity without many ...

30 ASTRONOMY • JULY 2018 LIGO’s two detectors and Virgo’s one are designed so the photodetectors record nothing if the arms stay ...

WWW.ASTRONOMY.COM 31 Jesse Emspak is a science writer who lives and works in New York City. equation, E=mc^2 .) But at a certain ...

32 ASTRONOMY • JULY 2018 (200,000 km/h). Usually, Perseid meteors appear white or bluish white. In 2018, the New Moon fortuitous ...

WWW.ASTRONOMY.COM 33 morning, so work commitments may limit the number of people who actually view the shower. For many amateur ...

Looking northeast 2 A.M., August 13 Polaris Radiant Algol Pleiades Capella Aldebaran ARIES PERSEUS TAURUS AURIGA 10° 34 ASTRONOM ...

WWW.ASTRONOMY.COM 35 in the United States who can spend the night outdoors should begin observ- ing at the end of astronomical t ...

10° SCORPIUS AQUILA AQUARIUS CAPRICORNUS SAGITTARIUS Saturn Mars Altair Late July, 10 P.M. Looking southeast Mars at its peak (^ ...

10° Radiant July 30, 2 A.M. Looking south-southeast CETUS AQUARIUS CAPRICORNUS GRUS Moon Fomalhaut Southern Delta Aquariid meteo ...

CAMELOPARDALIS URSA MINOR CASSIOPEIA LACERTA CORONABOREALIS CEPHEUS LYRA VULPECULA SAGITTA DRACO HERCULES PEGASUS ANDROMEDA CYGN ...

LEO MINOR BOÖTES COMABERENICES CANES VENATICI LEO URSA MAJOR VIRGO HYDRA LIBRA UPUS M104 M5 M51 M Arcturus M64 NGP Denebola Spic ...

PATHOF THE PLANETS The planets in the sky These illustrations show the size, phase, and orientation of each planet and the two b ...