Mercury down under

Feb 27, 2012 by Jason Major, Universe Today
MESSENGER wide-angle camera image of Mercury's southern hemisphere.

NASA’s MESSENGER spacecraft, about to wrap up its first full year in orbit around Mercury, captured this view of the planet’s heavily-cratered southern hemisphere on August 28, 2011. Because of its orbit, MESSENGER gets particularly good panoramic views of Mercury’s underside.

Here’s why…

MESSENGER’s orbit, established on March 18, 2011 at 00:45 UTC, is not a simple circling path around the first rock from the Sun. Instead it is highly elliptical, bringing it 124 miles (200 km) above ’s north pole at its closest and more than 9,420 miles (15,193 km) from its south pole at its farthest! (See diagram below.)

Three perspectives of MESSENGER's orbit. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. 

The close approaches over the northern hemisphere allow MESSENGER to study the Caloris basin, Mercury’s largest surface feature and, at over 960 miles (1,550 km) across, one of the largest impact craters in the entire Solar System.

The view of Mercury’s southern hemisphere above features some notable craters as well: the relatively youthful 444-mile (715-km) -wide Rembrandt basin is seen at top right, while the smaller pit-floor crater Kipling can be discerned to its left, just below the planet’s limb.

When craters are larger than 300 km in diameter, they are referred to as basins.

During its 12 months in orbit MESSENGER will have experienced only two days on Mercury! This is because Mercury rotates very slowly on its axis, completing a full solar day (sunrise to sunrise) every 176 Earth days. (And you thought your work day seemed to last forever!)

Find out more about the MESSENGER mission here.

Explore further: Curiosity brushes 'Bonanza king' target anticipating fourth red planet rock drilling

add to favorites email to friend print save as pdf

Related Stories

More 'hollowed ground' on Mercury

Jan 05, 2012

The latest featured image from NASA’s MESSENGER spacecraft, soon to complete its first year in orbit around Mercury, shows the central peak of the 78-mile (138-km) – wide crater Eminescu surrounded ...

Bright peaks, dark shadows

Feb 20, 2012

The 68-mile (109-km) -wide Amaral crater on Mercury reveals its brightly-tipped central peaks in this image, acquired by NASA’s MESSENGER spacecraft on Feb. 4, 2012. Long shadows are cast by the crater’s ...

MESSENGER Returns Images from Oct. 6 Mercury Fly-By

Oct 07, 2008

MESSENGER is the first mission sent to orbit the planet closest to the sun. On Oct. 6, 2008, at roughly 4:40 a.m. ET, MESSENGER flew by Mercury for the second time this year. During the encounter, the probe ...

Incredible ‘sideways’ look at Mercury’s limb

Nov 29, 2011

Wow -- just wow! Here’s a unique, jaw-dropping, and beautiful look at Mercury from the MESSENGER spacecraft, in a mosaic created from nine images taken by the Narrow Angle Camera (NAC) of the Mercury ...

See Mercury at sunset

Mar 15, 2011

The timing couldn't be better. Just as NASA's MESSENGER probe is about to enter orbit around Mercury, the innermost planet is popping out of the twilight for its best apparition of 2011.

Recommended for you

Australian amateur Terry Lovejoy discovers new comet

3 hours ago

It's confirmed! Australian amateur astronomer Terry Lovejoy just discovered his fifth comet, C/2014 Q2 (Lovejoy). He found it August 17th using a Celestron C8 fitted with a CCD camera at his roll-off roof ...

Students see world from station crew's point of view

Aug 19, 2014

NASA is helping students examine their home planet from space without ever leaving the ground, giving them a global perspective by going beyond a map attached to a sphere on a pedestal. The Sally Ride Earth ...

Mars deep down

Aug 19, 2014

Scarring the southern highlands of Mars is one of the Solar System's largest impact basins: Hellas, with a diameter of 2300 km and a depth of over 7 km.

User comments : 0