Astronomy

ASTRONEWS

134,

Numbers shown in miles per hour

Mercury

Venus

The Moon

25,03123,

Earth

Mars

11,252 5,

9,

Pluto

2,

47,

Uranus

52,

Neptune

Saturn

80,

Jupiter

130,

120,

110,

100,

90,

80,

70,

60,

50,

40,

30,

20,

10,

0

FAST

FAC T

WWW.ASTRONOMY.COM 13

HOW FAST MUST A ROCKET TRAVEL

TO LEAVE EACH PLANET?

Roughly 1 in 1,000 massive galaxies are consid-

ered “relics” that stopped growing during devel-

opment. These stagnant galaxies are usually too

far away for detailed observation, but NASA’s

Hubble Space Telescope recently found one

right in our local neighborhood.

NGC 1277, about 240 million light-years away,

has remained more or less the same for the last

10 billion years. During its early years, NGC 1277

popped out stars 1,000 times faster than the

Milky Way does today. NGC 1277’s halt in galactic

development left it with twice as many stars as

our own galaxy, at only a quarter of its size.

Astronomers identified this oddball when

they saw its staggering amount of red globular

clusters, which are thought to form along with

the galaxy, and the near absence of blue globu-

lar clusters, which show up later on as the galaxy

absorbs surrounding satellite galaxies. The dis-

crepancy hints that NGC 1277 never swallowed

up other galaxies. Another sign that NGC 1277 is

a relic is its abnormally large supermassive black

hole. It likely grew concurrently with the galaxy,

but because so little stellar material surrounds it,

the black hole appears large in comparison.

NGC 1277’s lack of growth is likely due to its

location and speed. It’s racing through the cen-

ter of the Perseus Cluster, which houses more

than 1,000 galaxies, at roughly 2 million mph

(3.2 million km/h), moving too fast to either

merge with other galaxies or acquire their out-

lying stars. Nor can it pull in the gas needed for

additional star formation; even if it could

absorb material, the gas in Perseus’ center is

too hot to condense and form stars.

Looking forward, researchers hope to use

NASA’s James Webb Space Telescope, set to

launch in 2020, to further study NGC 1277 and

measure the amount of dark matter it contains.

— Amber Jorgenson

Oddball galaxy

stopped growing

too soon

Chandra updates

the Crab Nebula

To leave the solar system, you must

attain a speed equal to the Sun’s

escape velocit y: 1,381,308 mph.

X-RAY: NASA/CXC/SAO; OPTICAL: NASA/STS

CI; INFRARED: NASA/JPL-CALTECH

OUT OF HERE. The speed any object must reach to escape the gravitational pull of a body in space

is called the escape velocity of that body. For example, a rocket leaving Earth for the Moon must travel

at 25,031 mph (40,283 km/h). Other planets and satellites have different masses than our world, so

their escape velocities are either more or less

than Earth’s. — Michael E. Bakich

ASTR

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ARRESTED DEVELOPMENT. NGC 1277 is a galaxy in a nearby cluster that abruptly stopped growing.

Today, it is dominated by old, red globular clusters and aging stars born 10 billion years ago. Astronomers

believe that its location and speed in the cluster are responsible for its lack of continued growth.

POPULAR DESTINATION. NASA’s Chandra X-ray

Observatory, which celebrates its 20th anniversary

next year, continues its historic relationship with

the Crab Nebula with this composite image. The

Crab Nebula was one of Chandra’s first targets after

it launched in 1999, and it has been the subject of

frequent study ever since. This photo combines

Chandra’s X-ray observations, shown in blue and

white, with infrared imagery from NASA’s Spitzer

Space Telescope, shown in pink, and optical data from

NASA’s Hubble Space Telescope, shown in purple. The

nebula dates back to A.D. 1054, when observers from

around the world reported seeing a “new star” in

the constellation Taurus the Bull. Knowing when the

central star exploded has allowed researchers to keep

a detailed timeline of the Crab Nebula’s formation and

evolution, making it a prominent target for continued

research. — A.J.

NASA, ESA, M. BEASLEY (INSTITUTO DE ASTROFÍSICA DE CANARIAS), AND P. KEHUSMAA

WETTER WORLDS. The planets around TRAPPIST-1 are estimated to be between 15 and 50 percent water

by mass. Earth is only 0.02 percent.