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An impressionist view of part of our solar system

The Planets

Professor Brian Cox explores the dramatic lives of the eight majestic planets that make up our Solar System.

About the programme

In this major new landmark series, Professor Brian Cox tells the extraordinary story of our Solar System's four and a half billion years of history, filled with spectacle and drama. Using the data from our very latest explorations of the Solar System combined with ground breaking CGI this series will reveal the beauty and grandeur of eight planets whose stories we are only just beginning to understand. One family. Worlds apart.

To find out more or to watch on iPlayer go to the BBC programme pages .

Professor Brian Cox on location at Bandar Al Khiran in Oman

Copyright: Brian Cox

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Image of Venus and Neptune together.

The Weather on all 8 Planets of our Solar System

Ever wondered how the weather differs on Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune? Professor Stephen Lewis investigates...

Seven of the eight planets in the Solar System are surrounded by atmospheres. Atmospheres also surround some of the larger moons, such as Saturn’s moon Titan, and even Pluto, a Kuiper Belt object, possesses a tenuous atmosphere when ices are vaporized from its surface.

On Earth, the weather impacts on all our lives and activities. The weather is determined by the motion and state of the atmosphere and can change from day-to-day or even hour-to-hour in many places. Weather is different from climate, which can be thought of as the average conditions in an area over a longer period of time. Climate changes happen over timescales of decades to millions of years.

Just like the Earth, each planetary atmosphere has its own, often extreme and sometimes beautiful, weather patterns and phenomena.

What drives the weather?

Image of the burning Sun emitting solar flares

The energy supply that powers most weather on Venus, Earth and Mars is light (including ultraviolet light) from the Sun. Over the year, the regions of each planet near the equator are heated more than the poles. The atmosphere moves in response to this unequal heating, transporting heat from warmer to cooler regions. These motions are reflected in the high and low pressure weather systems that move across those of us who live in middle latitudes. In essence, the weather is solar-powered.

The amount of power radiated by the Sun is enormous, roughly 1.4 kW/m2 at the distance of the Earth. Allowing for scattering back to space by clouds and ice, and on average over the year and time of day, about 200 W/m2 of this solar radiation reaches the Earth’s surface. But near the equator this is more than 300 W/m2 and near the poles less than 100 W/m2. Only the distant Giant Planets, Jupiter, Saturn and Neptune, emit their own internal heat at a rate similar to the power that they receive from the Sun (which is very much less out at their orbits, Neptune only receives about 1/900th of the solar radiation per m2 that the Earth does, since it is about 30 times further from the Sun).

There are two important influences that modify the response of an atmosphere to this heating.

The first is gravity, which not only prevents the atmosphere from quickly escaping to space, but vertically stratifies the air so that air density decreases exponentially with increasing height and ‘buoyancy waves’ (similar to waves on the surface of the sea) can form within layers of the atmosphere. These waves can often be seen in thin sheets of cloud.

The second is the rotation of the planet, which seems to deflect winds to their right in the northern hemisphere (left in the southern hemisphere), the ‘Coriolis effect’ . We might believe that we are almost stationary for most everyday purposes, but in fact the Earth is rotating very rapidly on its axis (once every 23 hours 56 min; a solar day is a little longer, 24 hours, since the Earth also moves around the Sun in its annual orbit and so it takes another 4 min to rotate completely relative to the Sun) so that at the latitude of the UK we are constantly moving eastwards at over 1000 km/h compared to the Sun and stars. We experience the weather from that rotating viewpoint: a wind curves as we watch it move across the rotating Earth’s surface.

The Coriolis effect only applies to very large-scale motions (or to very fast ones) and is not readily apparent in most other human-scale experiences. Contrary to a popular myth, water does not rotate in opposite directions when going down the plughole in different hemispheres, because other factors (such as the shape of the basin, the way the water was moving when the plug was pulled out, etc.) are vastly more important on those scales. It is possible to experience the Coriolis effect in action on smaller scales if you are rotating more rapidly. Try to throw or roll a soft ball on a rotating roundabout; if the roundabout is rotating anticlockwise, the ball will seem to curve to the right of your intended target. 


Mercury

Image of Mercury

Mercury is the only planet in the solar system not to be surrounded by a substantial atmosphere. One reason for this is Mercury’s relatively small mass and hence gravitational field, only about a third that of the Earth, which means that it is easier for gases to escape to space. The other reason is related to Mercury’s proximity to the Sun: any gases around the planet are heated and rapidly stripped away by collisions with the flow of energetic particles known as the ‘Solar Wind’. Other planets lose atmospheric gases to space as well, but at slower rates, generally because they have a stronger gravitational field (except for Mars, which is similar to Mercury) and, crucially, they are all further from the Sun. Only a few of the lightest and most energetic gas atoms can escape from the gravity field of a Giant Planet, like Jupiter, and a smaller proportion have the high energies required in the cold upper atmosphere temperatures of the outer solar system.


Venus

Image of Venus

Venus is shrouded in a dense layer of clouds which scatters most sunlight back out to space. This is why it appears bright and almost featureless to the eye in the early morning or evening sky. It has long been thought that Venus is warmer than the Earth, as it is only two-thirds of the distance from the Sun, and it was once believed that it might harbor a lush, tropical climate underneath the cloud decks. The reality is not so pleasant. Venus’s clouds are at about the same pressure and temperature as those on Earth, but are made largely from concentrated sulfuric acid. The surface lies around 60 km below the clouds, at a pressure 95 times that on Earth. A runaway greenhouse effect means that temperatures are typically over 460°C, hot enough to melt lead. If Venus ever had oceans they have long since evaporated. No evidence remains on the surface, which is covered with more recent lava flows and scarred by huge faults and fractures.

One of the most interesting features of Venus is that it rotates very slowly, once every 243 Earth days, and in the opposite direction compared to the other planets (perhaps a result of large collisions very early in the planet’s history, which effectively turned the planet upside-down). This is less than one full rotation on its axis per Venus year (225 Earth days). The Coriolis effect is therefore of little importance on Venus and the atmosphere rises at the equator and sinks around the poles, like the circulation originally proposed for Earth by George Hadley in 1735, before the importance of rotation was fully understood (on Earth the ‘Hadley Cells’ only extend to roughly 30° latitude from the equator). Remarkably, the east-west winds at the height of the clouds on Venus reach over 340 km/h, meaning that the cloud decks rotate once around the planet roughly every 4 days, about 60 times faster than the solid surface beneath. This phenomenon is called ‘super-rotation’ and must be explained by complex interactions with wave-like features feeding momentum into the large super-rotating jet.


Earth

Image of Earth

The Earth’s atmosphere stands out in the solar system for its composition of nitrogen (78%), oxygen (21%) and argon (1%) with many other gases present in trace amounts. This composition is a result of the presence of life on the planet. Mars and Venus have primarily carbon dioxide atmospheres and the Giant Planets are mainly hydrogen and helium. Earth’s atmosphere was probably very different in the early stages of the planet, most obviously the oxygen levels that we see today only came about as the result of the evolution of blue-green algae between 2 and 3 billion years ago (about half the age of the planet).

Just as life has altered the atmosphere, it is the atmosphere that has made life on Earth possible. Without a ‘natural greenhouse effect’ (from the pre-industrial atmospheric composition), of about 35°C of warming, the surface would be frozen and life impossible. In contrast, Venus has boiled under a runaway greenhouse effect of almost 500°C, and Mars has frozen with a tiny natural greenhouse of about 3°C of warming from its present, thin atmosphere. One unique feature of the Earth is that it has a coupled ocean-atmosphere system, with water in the form of ice, liquid water and vapour in the air. This active water cycle has trapped higher levels of carbon dioxide into carbonate rocks and is vital for life.

Earth’s atmosphere gives rise to many spectacular weather events, just a few of which are described in more detail here.


Mars

Image of Mars

Mars has a pattern of seasons very much like those of the Earth, but its surface pressure is over one hundred times lower. The thin atmosphere means that the surface weather is often an exaggerated form of a desert on Earth: a relatively warm temperature, often above 0°C, on a summer’s afternoon and a freezing night, when temperatures can plunge by up to 100°C. Just like Earth, Mars has patterns of high- and low-pressure weather systems, especially in the winter hemisphere, but the atmosphere is very dry with only a few, cirrus-like clouds of fine ice crystals. The dry atmosphere means that Mars’s famous dust storms can last for months before the fine dust particles fall out of the atmosphere. On Earth, dust storms end more quickly as water condenses on the grains.

One interesting feature of Mars is that in the winter hemisphere it can become cold enough (around -130°C, depending on pressure) for the main atmospheric constituent, carbon dioxide, to freeze. This is unique amongst the planets, and contrasts with our own snow and ice formed of water, a relatively tiny proportion of the atmosphere (less than 0.005% by mass). In Martian winter a thick hood of carbon dioxide clouds forms over the pole and snows onto the surface, where carbon dioxide ice accumulates. About one third of the total atmospheric mass freezes onto the winter pole and sublimes again spring, to move to the opposite pole.


Jupiter

Image of Jupiter

Jupiter rotates extremely rapidly despite its great size, with a day less than 10 hours long, and is home to a vast array of jets and vortices. The atmospheric circulation of Jupiter is dominated by alternating, east-west jets which have created the banded appearance of the planet. Wind speeds can reach more than 600 km/h. Jupiter’s swirling clouds are what gives the planet its beautiful appearance. The high, white clouds consist of ammonia crystals, while the darker ones are deeper, water ice clouds. The clouds are coloured by a variety of chemicals, brought up from the deeper atmosphere, which react with sunlight.

A variety of white and coloured ‘spots’ appear within this jet pattern. These are long-lived storms that can persist for many years. The banded structure breaks down near the poles, where a beautiful pattern of vortices has recently been revealed by the NASA Juno spacecraft.

Jupiter’s ‘Great Red Spot’ is the largest and most famous example of a long-lived spot. It has been continuously observed since at least the nineteenth century, and it was possibly the feature seen either by Robert Hooke in 1664 or Giovanni Cassini in 1665 using early telescopes. The Great Red Spot is a high-pressure anticyclone, larger than the Earth, which overturns completely every six days and is perhaps similar to a ‘blocking high’ weather system on Earth, such as might bring long periods of stable, colder weather to Europe in winter. Despite the rapid, swirling motions within and around the vortex, the Great Red Spot has persisted for centuries rather than days or weeks.


Saturn

Image of Saturn

Saturn’s atmosphere has a banded structure, like that of Jupiter, but with even faster winds; the equatorial jet can reach speeds of 1,800 km/h. There are fewer obvious vortices than seen on Jupiter, but the North Pole shows a regular hexagonal structure in a polar jet stream. Sometimes bright storms appear on Saturn, like high thunderstorm clouds on Earth. The image shows the so-called ‘Dragon Storm’ seen by the Cassini spacecraft in September 2004 (a false colour scale has been used to emphasize atmospheric structures). The Dragon Storm was linked to radio signals probably caused by huge lightning discharges in the atmosphere. One interesting feature of this storm was that it was seen in the same place over several months, flaring up at different times. It is thus likely to be linked to events taking place deeper in the atmosphere.


Uranus

Image of Uranus

Unlike the ammonia clouds of Jupiter and Saturn, Uranus and Neptune have clouds of methane ice in their cold atmospheres. It is very difficult to see any features in the hazy atmosphere of Uranus in visible light, but the images above were made from the Keck telescope in the infrared part of the spectrum. These show a banded structure with jets and a few distinct atmospheric features. One fascinating aspect of Uranus is that it lies almost on its side, rotating about an axis tilted at 98° to the plane of its orbit. This results in an unusual pattern of seasons over its long year (about 84 Earth years). At some times of year, one pole points towards the Sun and the other is in an extended period of darkness, while over the course of a full orbit the poles receive more sunlight on average than the equator does. In the image shown here, Uranus is almost side-on to the Sun. Only Voyager 2 has flown past Uranus, and it may be decades before another mission visits the system and observes it in more detail.


Neptune

Image of Neptune

When Voyager 2 flew past Neptune it saw a large anticyclonic storm, south of the equator, which was soon called the ‘Great Dark Spot’ because of its apparent similarities to Jupiter’s Great Red Spot. A smaller spot lay further south. The Great Dark Spot had vanished when the Hubble Space Telescope looked for it again five years later, although another feature appeared in the northern hemisphere. Despite its large distance from the Sun and relatively small solar energy input, Neptune exhibits the highest wind speeds recorded in the solar system, reaching 2,200 km/h.

Neptune has an interior heat source comparable with the small amount of energy it receives from the Sun, as do Jupiter and Saturn. Intriguingly, Uranus has no similar excess of heat. The ultimate source of this heat is gravitational energy; heat is generated either as the Giant Planets slowly contract or as heavier elements fall towards their centres. What role, if any, the interior heat source plays in driving weather systems remains mysterious and the subject of research.


Jupiter against black space

From Neptune's blue hue to Jupiter's red spot

Are the colours of the planets real? Do images of planets produced from spacecraft data really illustrate the true look of each planet? Professor David Rothery investigates...

These days, we’re used to seeing pictures of planets sent back by spacecraft. Some pictures look colourful, others less so. But do they show what each planet really looks like?

The short answer to this is “sometimes”, because some planets are genuinely quite colourful. Others are surfaced by rock that is almost entirely grey, and if you come across a picture of these looking colourful you can be pretty sure that the image has been manipulated in some way. Usually it’s a way of exaggerating subtle differences that human eyes are not good at seeing without help.

Anyone who has used a smartphone to take photos has probably stumbled upon various options to exaggerate or tone down the colour. Similar techniques are routinely used for processing images sent back by spacecraft, almost always to exaggerate colour rather than to make it more subtle.

But a camera on a spacecraft rarely sees colours in the same way as the human eye. For example, the red, green and blue components are usually recorded separately, transmitted to Earth as three separate black-and-white images and combined in colour only for display purposes. How the colours come out is bound to be at least subtly different from the ways your eyes would perceive the same view.

What’s more, the colours on an image don’t necessarily correspond to the original colours, even if there has been no attempt to exaggerate them. In principle, a spacecraft camera can record in any part of the light spectrum. When one of the channels lies beyond the visible range, such as in ultraviolet, we still have to use either red, green or blue to display it. That means the resulting picture is “false colour”, which might then be further exaggerated.

The giant planets

Jupiter's Great Red Spot

Jupiter’s Great Red Spot in natural colour, by NASA’s Galileo orbiter. NASA/JPL/Cornell University 

Jupiter famously has a “Great Red Spot ”, a giant oval storm system. While the more subtle colours elsewhere in Jupiter’s clouds may be largely due to the cloud-tops being seen through different depths of transparent atmosphere, the clouds in the spot itself are stained red by an unknown contaminant. Candidates include phosphorous, a sulfur compound, and complex organic molecules.

Jupiter’s propensity for strong colours is shared by its innermost large moon, Io. Here, frequent explosive volcanic eruptions shower the ground with sulfur and sulfur dioxide – making the globe look like a yellow pizza, scattered with black “olives” that are in reality patches of lava that are too fresh to have picked up a yellow stain yet.


Left: Io in natural colour. Right: Europa, in exaggerated false colour to accentuate the difference between ‘clean’ ice (blue) and ‘dirty’ ice (red). NASA/JPL/University of Arizona/DLR

Left: Io in natural colour. Right: Europa, in exaggerated false colour to accentuate the difference between ‘clean’ ice (blue) and ‘dirty’ ice (red). NASA/JPL/University of Arizona/DLR 

In contrast, the next moon out, Europa , has a surface made of frozen water. This is strongly reflective, making it bright but not very colourful. Most colour images of Europa that you are likely to come across are rendered in exaggerated and false colour.


Saturn

Saturn by NASA’s Cassini orbiter. This is a false colour image recorded using three infrared wavelengths, and shows patterns of thermal emission rather than reflected sunlight. NASA/JPL/ASI/University of Arizona

Saturn by NASA’s Cassini orbiter. This is a false colour image recorded using three infrared wavelengths, and shows patterns of thermal emission rather than reflected sunlight. NASA/JPL/ASI/University of Arizona 

Saturn has more muted colours than Jupiter, despite having a similar atmosphere. It’s natural colour is only vaguely yellow – any pictures you see of it looking strongly coloured are either false colour or exaggerated colour.

Saturn by NASA’s Cassini orbiter. This is a false colour image recorded using three infrared wavelengths, and shows patterns of thermal emission rather than reflected sunlight. NASA/JPL/ASI/University of Arizona 


Uranus and Neptune

A natural colour view of Neptune by NASA’s Voyager 2. NASA/JPL

A natural colour view of Neptune by NASA’s Voyager 2. NASA/JPL

Uranus and Neptune are also hidden by an immensely deep atmosphere. To our eyes, Uranus looks naturally green and Neptune blue, because the tops of their clouds of condensed methane are seen through a great depth of methane gas that filters out the red component of sunlight so that only green-blue light makes it down to the clouds and back out. There’s not much colour variation though; the highest clouds look white but everywhere else is blue or green.


Mars

Three versions of the same view on the surface of Mars from NASA’s Curiosity rover. Left: unprocessed. Middle: adjusted to how human eyes would see it. Right: how it would look under Earth-like lighting conditions (note how the colour of the sky has changed) NASA/JPL-Caltech/MSSS

Three versions of the same view on the surface of Mars from NASA’s Curiosity rover. Left: unprocessed. Middle: adjusted to how human eyes would see it. Right: how it would look under Earth-like lighting conditions (note how the colour of the sky has changed) NASA/JPL-Caltech/MSSS

Mars is aptly referred to as “the Red Planet”. The iron in its rock  and dust has largely been turned to iron oxide, or rust. Consequently, Mars looks red to the unaided eye if you see it in the sky, it looks red from orbit, and it looks red as seen by rovers on the ground. Here the debate is whether to render colours as they “really” look or as they would look if the quality of the light were the same as on Earth.

Three versions of the same view on the surface of Mars from NASA’s Curiosity rover. Left: unprocessed. Middle: adjusted to how human eyes would see it. Right: how it would look under Earth-like lighting conditions (note how the colour of the sky has changed) NASA/JPL-Caltech/MSSS


Venus

The cloud tops of Venus in natural colour, but with the brightness reduced and the contrast stretched to reveal structure. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The cloud tops of Venus in natural colour, but with the brightness reduced and the contrast stretched to reveal structure. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 

Venus is swathed in dazzlingly white clouds and the surface has been visited only by handful of Soviet landers. The dense clouds allow only a dull reddish glow to reach the ground, so everywhere looks orange. But the rocks themselves are really a drab grey kind of lava.


Mercury

00:45

False colour rendering of Mercury, by MESSENGER orbiter NASA/JHUAP{L/CIW

Mercury is an airless world  made of drab, dark grey rock with just a hint of redness. It reflects only about 7% of the sunlight falling on it, which is only slightly more than coal would, but it is three times closer to the sun than the Earth is, where the intense sunlight would make it look pretty bright even without adjusting the image brightness. However, to tease out the colour variations that lurk in Mercury’s landscape features, it is common practice to use false colour in a way that basically boosts the very subtle natural colour differences until they are glaringly obvious.

Don’t think of this as cheating. It is revealing truths about a world that you’d be able to see if your eyes and brain had evolved there, in order to maximise the available information.



How places on other worlds get their names

Names for features provide essential points reference on planetary surfaces. From volcanoes on Mars to scarps on Mercury. Professor David Rothery explains how planetary scientists choose these names.

Map of the Moon by Michael van Langren (1655). wikipedia

Map of the Moon by Michael van Langren (1655). wikipedia

The New Horizons  spacecraft, which flew past Pluto  in 2015, successfully completed a flyby  of “Ultima Thule”, an object in the Kuiper belt  of bodies beyond Neptune on January 1, 2019. The name Ultima Thule, signifying a distant unknown place, is fitting but it is currently just a nickname pending formal naming. The official names of the body and of the features on its surface will eventually be allocated (this could take years) by the International Astronomical Union (IAU) , which celebrates its centenary in 2019.

The IAU’s achievements during its first few decades include resolving contradictory sets of names given to features on the Moon and Mars by rival astronomers during the previous few centuries. The nomenclature working group’s task would then have been largely over, had the space age not dawned – allowing space probes to send back images revealing spectacular landscape details on planets and their moons.

Planetary scientists would find life difficult without names for at least the largest or most prominent features on a body. If there were no names, the only ways to be sure that other investigators could locate the same feature would be by numbering them or specifying map coordinates. Either option would be cumbersome and unmemorable.


The rules

Approved names on global topographic map of Mars. USGS 

Approved names on global topographic map of Mars. USGS 

Building on some of the already entrenched lunar and martian names, the IAU imposed order by establishing themes for the names of features on each body. For example, large craters on Mars are named after deceased scientists and writers associated with Mars (there’s an Asimov and a Da Vinci), and craters less than 60km across are named after towns and villages on Earth (there’s a Bordeaux and a Cadiz).

Apart from craters, most names are in two parts, with a “descriptor term”  of Latin origin added to denote the type of feature that has been named. On Mars we find neighbouring valleys called Ares Vallis, Tiu Vallis and Simud Vallis, in which the descriptor term “Vallis” is Latin for valley. This is preceded by the word for “Mars” in a different language – in these examples Greek, Old English/Germanic and Sumerian respectively. Among other descriptor terms are Chasma (a deep, elongated depression), Mons (mountain), Planitia (a low lying plain) and Planum (a high plain or plateau).

Descriptor terms are chosen to avoid implying that we know how any particular feature formed. For example, there are many scarps on Mercury that are currently interpreted as thrust faults  (where one region of a planet’s surface has been pushed over another). However, a neutral descriptor term – in this case Rupes (Latin for scarp) – is used so they would not have to be renamed if we were to realise that we’d been misinterpreting them. Similarly, none of the giant mountains on Mars that are almost certainly volcanoes has volcano as a formal part of its name.

The largest volcano on Mars, Olympus Mons , coincides with an ephemeral bright spot that can sometimes be discerned through telescopes. Though this was initially dubbed Nix Olympica (meaning “the snows of Olympus”) by the 19th-century observer, Giovanni Schiaparelli , space probes have since shown that the temporary brightness is not snow but clouds that sometimes gather around the summit. The IAU decided to keep the Olympus part of the name, qualified by the more appropriate descriptor Mons (mountain in Latin).

On the Moon, the IAU retained Mare (Latin for sea) as a descriptor term for dark spots, even though it is clear they have never been water-filled as was once thought. However, Michael van Langren’s Mare Langrenianum, which he immodestly named after himself on his 1655 map, is now Mare Fecunditatis .


Cultural balance

A map of part of Io, with names added. USGS

A map of part of Io, with names added. USGS

The IAU is rightly sensitive to achieving cultural and gender balance. The names of lunar craters that the IAU inherited commemorate famous past scientists, which for historical reasons are dominantly male and Western. In partial compensation, the IAU decided that all features on Venus, whose surface was virtually unknown because of its global cloud cover until we got radar spacecraft  into orbit, would be named after females (deceased or mythical). For example, there is a Nightingale Corona , a large oval-shaped feature named after Florence Nightingale. The only non-female exceptions are three features that had already been named after being detected by Earth-based radar.

Prior to the first detailed images of Jupiter’s moons by Voyager-1  in 1979, the IAU planned to use names from the myths of peoples in Earth’s equatorial zone for the moon Io. It would use mythical names from the European temperate zone for Europa, names from near-Eastern mythology for Ganymede and names from far northern cultures for Callisto.

They stuck to the latter three, and so Europa has Annwn Regio (a region named after the Welsh “Otherworld”), and Ganymede and Callisto have craters named Anubis (Egyptian jackal-headed god) and Valhalla (Norse warriors’ feast hall).

However, because Io was revealed to be undergoing continual volcanic eruptions, the original naming theme was deemed inappropriate and was replaced by the names of fire, sun, thunder/lightning and volcano deities from across the world’s cultures. For example, the names Ah Peku, Camaxtli, Emakong, Maui, Shamshu, Tawhaki, and Tien Mu (which occur on the map above) come from fire, thunder or Sun myths of the Mayans, the Aztecs, New Britain, Hawaii, Arabia, the Maoris, and China, respectively.


Captain Cook and the Maoris

Endeavour Rupes, the shadowed escarpment in the middle of a 400km wide view of Mercury. NASA/JHUAPL/CIW

Endeavour Rupes, the shadowed escarpment in the middle of a 400km wide view of Mercury. NASA/JHUAPL/CIW

The IAU has struggled to achieve cultural balance for some features. For example, the theme  for Rupes on Mercury is “ships of discovery or scientific expeditions”. By the nature of world history, there is a preponderance of Western ship names. For example, we find Adventure, Discovery, Endeavour, and Resolution – all four ships from Captain Cook’s  18th-century voyages to the Southern Ocean and Pacific.

Read more: Mysterious red spots on Mercury get names – but what are they? 

Personally, I am content that these were primarily journeys of scientific discovery  rather than of conquest or colonisation. Cook’s first voyage was undertaken to observe a rare transit of Venus , and his second voyage reached further south than ever before.

That said, it would be nice to redress the balance. In connection with a European planetary mapping project , one of my PhD students and I hope to get at least one of Mercury’s as yet unnamed Rupes named after a canoe in which the Maoris arrived in New Zealand.

Ultimately, space exploration is for all of humanity.




This article is republished from The Conversation  under a Creative Commons license. Read the original article .


Meet the OU experts

A photograph of Professor Stephen Lewis
Professor Stephen LewisProfessor of Atmospheric Physics - School of Physical SciencesVIEW FULL PROFILE
A photograph of Professor Stephen Lewis
Professor Stephen LewisProfessor of Atmospheric Physics - School of Physical Sciences

Stephen Lewis is Professor of Atmospheric Physics at The Open University. His research interests include the dynamics of planetary atmospheres and using computer modelling to understand spacecraft observations. He has worked on subjects including Mars, Venus, the Giant Planets, Exoplanets and the climates of Earth and Mars in the distant past. Results from Stephen’s work have been used by both ESA and NASA in planning space missions, in particular for Mars exploration.

Stephen was an academic consultant on the series and co-author of the associated poster.

A photograph of Professor David Rothery
Professor David RotheryProfessor of Planetary Geosciences - School of Physical SciencesVIEW FULL PROFILE
A photograph of Professor David Rothery
Professor David RotheryProfessor of Planetary Geosciences - School of Physical Sciences

David Rothery is Professor of Planetary Geosciences at The Open University. He began his career as a geologist using satellite images to help make geological maps of parts of the Earth, and now uses similar techniques to map parts of other planets. He is on the European Space Agency team that sent BepiColombo towards Mercury in 2018, and is funded by the European Commission on ‘PlanMap’, a project to boost European capability in planetary mapping.

David was an academic consultant on the series and co-author of the associated poster.

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