by Kim Malville
Venus will be obvious in the mornings of the beginning of February. It will be the brightest object above the southeastern horizon. Mercury will be close to the horizon and difficult to see for those who live close to the mountains. To the far right of the arc of planets is Jupiter, brighter than any star in the sky, but still not as brilliant as Venus. In between are four bright objects, two stars and two planets: Antares, Spica, Saturn and Mars. This a rare alignment that hasn’t occurred for more than 10 years, so it is worth at least one early rising during the first week of February. This arc of planets is about 110 degrees in length along the ecliptic, the path the sun takes across the sky. The planets do not stray far from the path. Not surprisingly the maverick in our original collection of nine planets is Pluto, which, as well all known, is not a planet but a dwarf planet. Its orbital characteristics are substantially different from those of the planets. Pluto’s orbit carries it by more than 17° above and below the ecliptic and sometimes inside the orbit of Neptune. For these and other reasons it was demoted in 2006 by those who attended the meeting of the International Astronomical Union in Prague. Now it turns out that the Caltech astronomer, Mike Brown, who has been vilified by Pluto-lovers for the significant role he played in the demotion of Pluto and for his book How I Killed Pluto and Why It Had It Coming has something new up his sleeve. Read on.
Breaking news: There may be a ninth planet
Out beyond Neptune, in addition to Pluto there are thousands of small icy objects, similar in size to Pluto or smaller, known as Kuiper Belt Objects (KBO). Just recently their orbits have been carefully measured, and two astronomers, Mike Brown and colleague Konstantin Batygin at Caltech, have found that their long axes are oriented in a peculiar way, suggesting the gravitational influence of an undetected massive planet lying far beyond.
This object, which they have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it is so far from the earth that this new planet may take between 10,000 and 20,000 years to make just one full orbit around the sun. Brown notes that the putative ninth planet—at 5,000 times the mass of Pluto—is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighborhood of the solar system. In fact, it dominates a region larger than any of the other known planets, which Brown claims could make it the most “planety” of the planets in the solar system.
Where did our putative Planet Nine come from and how did it end up in the outer solar system? We have long believed that the early solar system began with four planetary cores that went on to grab all of the gas around them, forming the four gas planets—Jupiter, Saturn, Uranus, and Neptune. Over time, collisions and ejections shaped them and moved them out to their present locations. “But there is no reason that there could not have been five cores, rather than four,” says Brown. Planet Nine could represent a fifth core, and if it got too close to Jupiter or Saturn, it could have been hurled outward into the darkness of the edge of the solar system. Brown has been receiving hate male for the past decade, including letters from school children showing cartoons of Pluto the dog, crying in despair at becoming a dwarf. Whatever happens, I suspect Brown is worthy of a little absolution if he can find this planet and make the solar system well again with nine genuine planets.
A splendiferous supernova
A fantastically small and extremely bright object that first appeared last June could be the brightest, most powerful supernova ever spotted by astronomers. It has more than 20 times the brightness of all the stars in our Milky Way Galaxy, is 570 billion times brighter than the Sun, and lies at a distance of 3.8 billion light years. That, by itself, provides a powerful perspective on the immensity of our universe. The supernova actually occurred 3.8 billion years ago, and it has taken that much time for its light to reach the Earth.
What beggars belief is that this supernova is probably produced by the destruction of a neutron star, a tiny ball of compressed neutrons a mere 10 miles in diameter, but with a mass greater than the sun. It is spinning one thousand times a second, which means its surface is moving at some 30,000 miles per second, fast but still less than the speed of light. This neutron star has collapsed into such a tight ball that all of its electrons and protons have been forced together to form only neutrons. Its rapid spin has generated a magnetic field some 100 trillion times stronger than the Earth’s field. During the first four months since the supernova’s discovery it hase released as much radiation energy as our sun would produce in 90 billion years of shining.
Supernovae are the real heroes of our universe. They provide most of the elements in the world around us that are not hydrogen or helium. The oxygen, calcium, carbon, and nitrogen in our bodies, so very necessary for life, were produced by a supernova explosion in our galaxy long before the solar system was formed. The good news for astronomers is that the supernova is so bright it will be relatively easy to get high-quality observations. We’ll know more in the next few years about this astonishing object. We’re just very glad that it is not nearby! The supernova burn would be horrendous.