hellas planitia


hellas planitia, mars, photographed by mars express, 23rd january 2014.

37 to 49°s, along 70°e longitude. central hellas planitia, some of the lowest terrain on mars (about 8km below datum). the bottom of the image shows the hellas chaos. 

notice dark sand dunes in the 3rd and 5th images. the channel coming from left in the 1st image is enticingly sinuous, but i’d hesitate to speculate that it was eroded by water.

composite of visible light images, but the colour balance is not naturalistic.

image credit: esa. composite: ageofdestruction.

ellada: Clouds over Mars, photographed by Mars Global Surveyor, 2002.

10 photographs, about one a week, 19th October-30th December 2002; on Mars, Ls 84° to Ls 116°, the first third of the southern winter.

Hellas Planitia, a massive impact basin, spans the image. 7 km deep in places, Hellas covers about 12 million square km; for scale, the two largest countries on Earth cover 17 (Russia) and 10 million square km (Canada).

Image credit: NASA/JPL/MGS/MSSS. Animation: AgeOfDestruction.


clouds in hellas basin, mars, photographed by mars express, 7th june 2012.

24  to 33°s, 56 to 58°e; 4 to 6 km below the martian datum, on the northwest slope into to hellas planitia. the large crater at centre right is niesten, 115 km across.

composite of 8 images; 3 in visible light for colour (not adjusted to a naturalistic balance) and 5 for animation.

image credit: esa. composite & animation: ageofdestruction.


nicole: Clouds over Mars, photographed by Mars Global Surveyor, 2001.

13 pairs of images, taken through blue (left) and red (right) filters, 14th February-5th June 2001; Ls 117.0° to Ls 173.5°, the latter two thirds of the northern summer.

At the top of each gif is the north polar cap. The light area at the bottom is the northwest edge of the massive Hellas Planitia basin (the bright crater on its rim is Terby, 170km across). Left of centre are the Syrtis Major highlands; right of centre is the Isidis Planitia; you can definitely see clouds affected by the terrain’s change in altitude.

Image credit: NASA/JPL/MGS/MSSS. Animation: AgeOfDestruction.

Hubble takes Mars portrait near close approach

Bright, frosty polar caps, and clouds above a vivid, rust-colored landscape reveal Mars as a dynamic seasonal planet in this NASA Hubble Space Telescope view taken on May 12, 2016, when Mars was 50 million miles from Earth. The Hubble image reveals details as small as 20 to 30 miles across.

The large, dark region at far right is Syrtis Major Planitia, one of the first features identified on the surface of the planet by seventeenth-century observers. Christiaan Huygens used this feature to measure the rotation rate of Mars. (A Martian day is about 24 hours and 37 minutes.) Today we know that Syrtis Major is an ancient, inactive shield volcano. Late-afternoon clouds surround its summit in this view.

A large oval feature to the south of Syrtis Major is the bright Hellas Planitia basin. About 1,100 miles across and nearly five miles deep, it was formed about 3.5 billion years ago by an asteroid impact.

The orange area in the center of the image is Arabia Terra, a vast upland region in northern Mars that covers about 2,800 miles. The landscape is densely cratered and heavily eroded, indicating that it could be among the oldest terrains on the planet. Dried river canyons (too small to be seen here) wind through the region and empty into the large northern lowlands.

South of Arabia Terra, running east to west along the equator, are the long dark features known as Sinus Sabaeus (to the east) and Sinus Meridiani (to the west). These darker regions are covered by dark bedrock and fine-grained sand deposits ground down from ancient lava flows and other volcanic features. These sand grains are coarser and less reflective than the fine dust that gives the brighter regions of Mars their ruddy appearance. Early Mars watchers first mapped these regions.

An extended blanket of clouds can be seen over the southern polar cap. The icy northern polar cap has receded to a comparatively small size because it is now late summer in the northern hemisphere. Hubble photographed a wispy afternoon lateral cloud extending for at least 1,000 miles at mid-northern latitudes. Early morning clouds and haze extend along the western limb.

This hemisphere of Mars contains landing sites for several NASA Mars surface robotic missions, including Viking 1 (1976), Mars Pathfinder (1997), and the still-operating Opportunity Mars rover. The landing sites of the Spirit and Curiosity Mars rovers are on the other side of the planet.

This observation was made just a few days before Mars opposition on May 22, when the sun and Mars will be on exact opposite sides of Earth, and when Mars will be at a distance of 47.4 million miles from Earth. On May 30, Mars will be the closest it has been to Earth in 11 years, at a distance of 46.8 million miles. Mars is especially photogenic during opposition because it can be seen fully illuminated by the sun as viewed from Earth.

The biennial close approaches between Mars and Earth are not all the same. Mars’ orbit around the sun is markedly elliptical; the close approaches to Earth can range from 35 million to 63 million miles.

They occur because about every two years Earth’s orbit catches up to Mars’ orbit, aligning the sun, Earth, and Mars in a straight line, so that Mars and the sun are on “opposing” sides of Earth. This phenomenon is a result of the difference in orbital periods between Earth’s orbit and Mars’ orbit. While Earth takes the familiar 365 days to travel once around the sun, Mars takes 687 Earth days to make its trip around our star. As a result, Earth makes almost two full orbits in the time it takes Mars to make just one, resulting in the occurrence of Martian oppositions about every 26 months.