THE SOUTHWORTH PLANETARIUM 207-780-4249 www.usm.maine.edu/planet 70 Falmouth Street Portland, Maine 04103 43.6667° N, 70.2667° W Founded January 1970 "Made from the best stuff off Earth." THE DAILY ASTRONOMER Tuesday, January 12, 2016 A Plethora of Petite Pandoras Biologists have, rather foolishly, abandoned the notion of spontaneous generation: the concept that inanimate matter that can spontaneously generate living beings. For instance, the blend of rain water and dirt, apart from making mud, was once believed to have also spawned worms. Some scientists based this conclusion on their observation that worms seemed to proliferate after a rain storm. Subsequent research revealed that worms require moisture for respiration and therefore tend to remain in moist soil during dry conditions, but are able to ascend to the watery surface after a recent rain fall. Though modern scientists assert that inanimate matter can't procreate, one must recognize that biologists have not fully studied the mating habits of neglected paperwork. They haven't observed how the unprocessed invoices and incomplete spreadsheet print outs, when left alone on a darkened desk, will recognize each other as soul mates and in their coupling sire a proliferation of other paperwork that, if neglected, will, yield to the primal temptation and engender a litter of progeny that...and, well, enough said. The same occurs with the question slips that we stuffed inside Pandora's Jar. Over the last few weeks, these, too, have been left alone in, of all places, a star dome and now the smattering of parchment strips has expanded into a swarm. So, today, in an attempt to stem the flow, we have extracted those questions that require brief answers and have stuffed them all into one article. Do not infer from this completely pointless preface that we are displeased to receive questions. In fact, we enjoy receiving and answering them immensely. We're merely attempting to explain why we're offering not just one or two questions in today's DA. Incidentally, unless one is referring to caustic relatives, four hardly constitutes a plethora. We chose the word merely for alliteration. WILL SIRIUS ALWAYS BE THE BRIGHTEST STAR? No. Sirius is the brightest night sky star now owing to its close proximity to us: about 8.6 light years. It is certainly not the intrinsically brightest star in vicinity. Also, like all the other stars, Sirius moves and its position relative to the solar system is always changing. Presently, Sirius is moving toward the solar system at 5.5 kilometers per second. This decreased distance will enhance its brightest over time. However, Vega, which is intrinsically brighter than Sirius, moves toward the solar system presently at 13.4 kilometers per second. Of course, Vega is about 26 light years away and now appears slightly dimmer than Sirius. However, in about 200,000 years, Vega will appear as bright as Sirius and then will become brighter. Even though it will remain more distant than Sirius, it is a more luminous star and will eventually become the brightest star in Earth's sky. DO OTHER PLANETS HAVE AURORA DISPLAYS? Yes. Aurorae have been observed on Jupiter, Saturn, Uranus, Neptune, Venus, and Mars as well as on Earth. Astronomers have not observed aurora on Mercury, nor should we have expected them to, as Mercury lacks an atmosphere. Aurora occur when charged solar particles excite the atoms within a planet's atmosphere. When excited, the electrons within the atoms are elevated to higher energy states. When these electrons settle down to their original states, they emit photons. These photons will not only be within the visible light spectrum, of course. We notice that Jupiter's aurora displays, for instance, consists of ultra violet photons. [If you consult the Daily Astronomer web-page, you can see images of the aurora elsewhere in the solar system: http://usm.maine.edu/planet/da-7-december-2015 ] DO WE GET HEAT FROM THE STARS? Yes, BUT, the heat is so slight as to be negligible. Let's regard Sirius, for instance. It is the brightest night sky star and presumably would impart more heat onto Earth than any other star, apart from the Sun, of course. Scientists have estimated this heat to be equivalent to that of a candle 3.5 miles from you. Sirius is giving me as much heat energy as a smoker down on the wharf provides me every time he ignites his Zippo. Though the stars are immensely hot, they are also far away. Light and heat energy diminish with the square of the separation distance. Let's imagine you are standing three feet from a flame. If you double your distance from that flame, the heat energy it imparts onto you will be reduced to one fourth of the original amount. When one is dealing with distances in light years, the reduction is highly significant. CAN ASTRONOMERS EVER DIRECTLY SEE EXO PLANETS? Yes they can and have directly "imaged" exo planets, those planets in orbit around other stars. Capturing direct images proves exceedingly difficult because a planet's reflected light is often overwhelmed by the star's light. However, if the star is sufficiently large and reflects a lot of its incidental light, it can be resolved as a separate image. Also, if a planet radiates copious heat energy, it will produce a bright infra red image. As long ago as 2004, astronomers captured a separate image of 2M1207b, a planet revolving around a brown dwarf. The Hubble Space Telescope imaged an exo-planet around the star Fomalhaut in 2008. Other exo planets have been directly imaged since this discovery. Astronomers are also now using coronagraphs, which are telescope attachments designed to block a star's light. This occultation enables astronomers to capture separate image of the star's attendant bodies, such as planets. Written by Edward Gleason Manager, Southworth Planetarium