Europa

Europa

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Here in the valley of Lecrin in Andalucia, southern Spain, about fifty people gathered to watch the Blood Moon on the evening of the 27th July, at La Conca Arts Club, next to the lake at Beznar. We had my old 4” Vixen refractor telescope on an equatorial mount, a pair of superb 16x70APM binoculars on a tripod, and others had brought various other binoculars, and a small Celestron reflector that some of the children had for Christmas. The seeing conditions that night, other than when the Moon came out of the shadow of the Earth around 0130-0200hrs in the early morning were superb.

Besides the obviously exciting event itself, there was plenty more to be seen that night. The incredibly bright Venus in the constellation Leo following the setting Sun, and to the south of us, magnificent Jupiter, “King of the Planets” in Libra. In the south east you could see the most beautiful planet in the solar system, Saturn, tracking its way through the dense star fields of Sagittarius, and then low in the east the dazzling red planet Mars, moving through the constellation of Capricornus.

The Blood Moon lived up to all expectations, I think everyone thoroughly enjoyed the spectacle, but some people were already interested in seeing the other planets and the brightest, in the best place was Jupiter and interesting, because as you could see our own moon, you could also see all four Galilean moons, Io, to the left of Jupiter and Callisto, Ganymede and Europa in that order to the right.

Europa (3100kms/1900mls) is similar in size to our own Moon (3475kms/2159mls), but there the similarities end, for the Moon, vital though it may be to the existence of life on Earth (see: What if there was no Moon, KCW Today June 2000), is a rocky, dead world. Europa on the other hand is an ice moon, suspected of harbouring a subterranean ocean, and the subject of numerous projected NASA and ESA missions in the early to mid-2020’s.

In 1610 when Galileo Galilei discovered the four moons of Jupiter, he could never have known that one, Io is the most volcanically violent place known anywhere and whose surface suffers a radiation intensity, greater than any other known object, 5 times the lethal dose for a human being, and that the other, Europa may be one of the prime candidates that harbour extraterrestrial life. Only after a series of spacecraft missions, the Voyagers in the 70s, Galileo in 1989 and New Horizons in 2007 was each moon transformed into a unique living world.

In the case of Europa, it was as if something had driven all over it, tracks crisscrossed its otherwise smooth white surface. Scientists analysed the data and realized that Europa is covered in floating ice sheets. These lineae (lines to the rest of us) indicate where sheets rub against each other and where water oozes into the airless sky and settles on both sides of the crevices to form parallel frozen hills. Meanwhile dark surface blotches appear as extended melt water features. Outside of the Earth these were the first known pools of water in the universe and when sodium atoms were discovered floating above Europa, it quickly became apparent that scientists were dealing with oceans of salt water, albeit deep beneath the icy crust.

The problem for scientists, is liquid water exists only in a very narrow pressure and temperature range. Europa is airless and cold between -160 and -220 Celsius, so something else must be at work. The pressure is exerted by the ice which is between 80 and 170kms thick floating on the surface. Then mighty Jupiter exerts its massive tidal forces and so do the other Galilean moons especially Io. Europa is tugged with every orbit, tidally stretching its entire body. The net result is a continuous heat supply, such that its oceans remain in liquid form. Just as with Earth, Europa was bombarded with icy comets containing complex amino acids, the building blocks of life. Since life began in Earths oceans there is no reason to suppose that the same processes couldn’t have simultaneously occurred on Europa, both have had 4.5 billion years to try, and we know one succeeded.

A 2016 study suggested that Europa produces 10 times more oxygen than hydrogen, which is very similar to Earth. Recently water plumes have been spotted jetting out from Europa’s South polar region suggesting active cryovolcanism and now scientists are suggesting that there is evidence for a form of plate tectonics, also considered helpful for the evolution of life. Spacecraft will visit and one day a lander will drill into the icy surface. The search for life other than ourselves, will never end, but one thing you can be sure of, no human is going there. Although not as bad as Io, Europa gets a steady 540 rads of daily radiation from Jupiter, enough to kill a human in 2 days. I think I’ll stick to La Conca Arts Club, the telescope and a bottle of fine Rioja.

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