In these warm May evenings, bring your binoculars and look for the four moons of Jupiter. It’s a great sight to see them changing their position each night. On May 1, to the west of Jupiter will be its most distant moon, Callisto and Ganymede. To the east and closer to the planet, you might be able to see its innermost moons, volcanic Io and watery Europa. For other nights of the moon, you can find a chart of the positions of the moons at https://in-the-sky.org/jupiter.php
Saturn rises around midnight at the first of the month and as early as 9:30pm at the end of the month. It is also in retrograde. Mars, red and dim, is in the western sky, visible for only 2 hours after sunset at the start of the month.
May 3: The moon will be close to Regulus, the brightest star in Leo, the Lion.
May 7: The nearly full moon will be within 3° of Jupiter and three times further away from Spica. Compare the steady light of Jupiter to the twinkling Spica.
May 10: Full moon
May 26: Thirty minutes after sunset look for a beautiful very slender crescent moon low in the west and below its will be ruddy Mars; binoculars will help.
May 30-31: The moon passes Regulus in Leo.
Plumes of water vapor on Europa
It was just announced the Hubble Space Telescope photographed what appears to have been a large plume of water vapor on Europa in February 2016, appearing at approximately the same place as one spotted in May 2014. The plume or geyser reached an extraordinary height of 60 miles, dwarfing any geyser we have on Earth.
We are not absolutely these bright spots on the side of Europa are plumes of water, but we do know there is that an ocean of liquid water beneath Europa’s icy shell, making this 1,900-mile-wide moon a great candidate in the solar system to contain alien life. In addition, thermal imaging performed by another spacecraft, Galileo, two decades ago, showed a “hotspot” at the location of the 2014 and 2016 plume candidates, where presumably warmer water from the interior may have erupted.
This detection of possible plumes could be a game changer and has already influenced the planning of NASA’s $2 billion Europa Clipper mission, which could be launched in the next five years. The plans are for the Clipper to go into orbit around Jupiter and perform 40 to 45 flybys of Europa over several years. Because of these recent discoveries, Clipper is now being designed to search for plumes and try to fly through them. Plume fly-throughs would allow Clipper to obtain samples of Europa’s buried ocean without having to land on its surface. Before the discovery of these possible plumes, the plan was to land a spacecraft on its surface and drill through the icy crust to reach the ocean. That would have been a very complex mission, because Europa lies in the midst of Jupiter’s radiation belt and is constantly struck by lethal doses of high energy particles.
Is there life in the water world of Enceladus?
The space craft Cassini has been exploring Saturn’s corner of the solar system for 13 years, zooming around its moons at a speed of 75,000 miles per hour, getting extraordinary pictures and data about its rings and moons. Cassini will forever get credit for discovering what may be the second (besides Europa) most likely place to find evidence of life beyond Earth, namely Enceladus. This strange little moon, a mere 300 miles in diameter, has some 100 geysers spewing forth plumes of salt water. Enceladus is mostly water — a water world. The plumes of liquid water erupt through cracks in its frozen surface. The plumes are like comets, containing a rich and fecund mixture of hydrogen, carbon dioxide, methane, ammonia, propane, acetylene, and formaldehyde- suggestive of some form of microbial activity in its deep, dark ocean. Microbes could obtain energy by the conversion of hydrogen, carbon dioxide, and water into methane, a process that is known as “the root of the tree of life on earth.” With luck it will also be a root of the tree of life on Enceladus.
The death dives of Cassini
On September 15, Cassini will make a fiery and lethal plunge into the atmosphere of Saturn, vaporizing within 3 minutes after entering the cloud tops.
Before its death, Cassini will plunge 22 times into the previously forbidden space between the clouds and the innermost ring. This area may be filled with small particles with which the spacecraft could collide and at its great speed could result in its immobilization or premature death. On the first of these plunges, occurring on April 26, the antenna will be facing forward, acting as a shield. That will be a very worrisome plunge for the spacecraft handlers back on Earth, because it will be more than an hour before its health will be known. In these plunges close to the rings, Cassini will produce all sorts of good data about the nature of the rings and their origins. For instance, it is not known if these rings are as old as Saturn itself, or were the result of the recent breakup of a lost moon some 100 million years ago. Slight gravitational pull by the rings on Cassini will also measure the mass of the billions of small particle that make up the rings.
One reason for this death by fire of this good friend of ours is to ensure that any of its earthborn microbes do not contaminate the biotic or prebiotic worlds of Saturn.