by Kim Malville
Jupiter will dominate our evening skies throughout June. This bright planet lies a little to the right of Spica throughout the month. It ceases its retrograde movement on June 9 and will progress toward Spica, passing it on September 11. Saturn rises at sunset and sets at sunrise throughout June. It reached opposition to the sun on June 14, which means it will be due south at midnight on that date.
June 1: First quarter moon
June 3: The moon passes within 2 degrees (four lunar diameters) of Jupiter.
June 9: Full moon. Look to the east for the rising moon with Saturn to its right.
June 17: Last quarter moon
June 20: The shortest night of the year in the northern hemisphere. Summer solstice occurs at 10:24pm.
June 27: The crescent moon will be within 1 degree of Regulus, the brightest star in Leo.
The red whale of Pluto
There’s a giant red “whale” on Pluto. This dark-colored region could be the remnants of a giant impact that produced Pluto’s moon Charon, some 4 billion years ago when the solar system was a dangerous place.
Pluto has become the most interesting non-planet in the solar system, and I am now beginning to wonder if we made a mistake in our vote back in 2006 at the meeting of the International Astronomical Union in Prague when we demote it to the status of a dwarf planet. That demotion did stir up controversy. Folks who loved the pup and transferred their affection to the planet were annoyed. Astronomers who had planned the New Horizons Mission were outraged that their space craft was no longer travelling to a full-fledged planet.
But, Pluto struck back on July 14, 2015, when the New Horizons Space craft flew past it at a very high speed and, quite amazingly, gathered a vast trove of information about the dwarf planet. It ranks up there with the strange and wondrous moons of Jupiter, volcanic Io and ocean-covered Europa and the geyser-spewing moon, Enceladus of Saturn. The plains on Pluto’s surface are composed of nitrogen ice, with traces of methane and carbon monoxide. The high sharp mountains are made of water ice. In addition to the red whale, known as Cthulhu Regio, there is the very puzzling Sputnik Planitia. This roughly circular area is a 600-mile-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal convection cells, looking like a giant lava lamp. Unlike the neighboring red whale, these up-surging convection cells have no impact craters, meaning that it’s a young surface where evidence of craters have been erased by the bubbling ice during the last 180,000 years. Note in the picture how rocky material that has fallen on the ice has been pushed to the boundaries by the flow of ice outward from the centers of the cells. The source of heat on this cold dwarf sufficient to produce this convection is a vexing puzzle.
The red whale, or Cthulhu Regio, some 1,850 miles long and 450 miles wide, is ground zero for the collision of an object about one-third the size of Pluto, that ripped away the crust of Pluto, producing its moon, Charon. That impact delivered organic compounds such as formaldehyde, commonly found in comets. Heat produced by the impact likely melted part of Pluto’s surface, forming pools of warm water into which formaldehyde flowed. These warm liquid water pools could not have lasted long on that very cold and dark world, but they apparently lasted enough to grow complex organic compounds with the red color that we now see. These are the same kind of compounds that may have been the progenitors of life on Earth. We, too, had a similar impact, when an object about the size of Mars hit the Earth and tore out enough matter to form our moon. Pluto is still being hit by small meteorites, producing craters that are shown on the body of the whale, which thus contains the memory of meteorite strikes spanning 4 billion years, very old and relatively recent. The memory of Sputnik Planita has been erased by the bubbling ices. This is truly Pluto’s revenge: besides Earth no other object in the solar system has such a complex and puzzling geology or, should we say, plutology.
Alien life may be closer than we once thought
How far beyond the solar will we have to travel to meet the nearest alien life? Astronomers are taking that question a bit more seriously as new models increasingly suggest that the closest Earth-like planet to our solar system could indeed be habitable. That planet is Proxima b, orbiting a dwarf star Proxima Centauri, a mere 4.25 light years away. With knowledge only of the luminosity of the star (1/600 that of the sun), the mass of the planet (1.3 times that of Earth), and the length of its year (11.2 days), a team from Great Britain have used climate models designed for the earth to predict that Proxima b has liquid water on its surface. They used a climate model designed for Earth—the Unified Model developed by the United Kingdom’s Met Office to show that under a wide variety of conditions, the planet could be warm enough for liquid water. The dwarf star around which the planet orbits is much cooler than the sun, and it has a much longer life than our sun, which will die in 5 billion years. (Sad, as Trump would say.) Proxima Centauri could last a whopping 4 trillion years or 300 times the current age of the universe. That seems more than enough time for life to develop and flourish on a warm, watery planet. The fly in the ointment is that Proxima Centauri is a magnetically active star that produces x-rays similar in quantity to the output of our sun. Orbiting close to its sun, the planet could be bathed in x-rays and other noxious radiation. Is that good or bad? A little radiation may be good thing, producing mutations, speeding up evolution, perhaps producing intelligent (but probably ugly) beings or fierce Godzillas. Or the planet may be a sterile wasteland. Only time will tell, as more telescopes on Earth and in space are being trained on the planet.