Astronomy - February 2014

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9.

BILLION

The number of years it has taken light

emitted from the most distant gravitation-

al lens to reach us. Astronomers describe

the discovery in the November 1 issue of

The Astrophysical Journal Letters.

A deep canyon on

the Red Planet

MARTIAN ABYSS. Located near Mars’ equator, Hebes

Chasma is a fissure some 200 miles (320 kilometers) long,

80 miles (130km) wide, and 5 miles (8km) deep. The

nearby volcanic Tharsis Region likely contributed to the

canyon’s formation. A large flat-topped mesa — span-

ning about 75 miles (120km) by 25 miles (40km) — fills

much of Hebes Chasma’s interior. Wind and water likely

shaped this structure, say scientists. The mesa is com-

posed of many layers of rock and debris, but the materi-

als look geologically different from the fissure’s. The walls

of the two bodies also appear to be weathering differ-

ently. Scientists with the European Space Agency’s Mars

Express mission released this composite image of the

Red Planet’s Hebes Chasma on October 10. It combines

eight images taken with the spacecraft’s High Resolution

Stereo Camera between 2004 and 2009. — L. K.

Hebes Chasma sits at the

northern edge of its big brother,

the vast Valles Marineris canyon

that stretches nearly 2,500 miles

(4,000 kilometers).

FAST

FACT

ESA/DLR/FU BERLIn (G. nEUkUM)

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