Bob Doyle, Columnist
Perhaps the best American magazine dealing with the Universe is “Sky and Telescope,” published monthly in Cambridge, Massachusetts.
Sky and Telescope recently came out with a special edition, “Astronomy’s 60 Greatest Mysteries.” Editor Robert Naeye and his staff developed 60 provocative questions and then interviewed leading researchers in each area.
The researchers were careful to present arguments supporting their views, but also considered the other side and its evidence.
There are beautiful astronomical images and diagrams on nearly each page. The 60 Cosmic Mysteries are divided into six areas: 1. Earth, 2. Solar System, 3. Planets Beyond our Sun and Extraterrestrial Life, 4. Stars, Supernovae & Black Holes, 5. Galaxies and the Universe, and 6. Space Exploration.
I will treat five questions, one from each of the first five areas. “Astronomy’s 60 Greatest Mysteries” has ISSN 0037 6604 with a list price of $8.99. Most book stores should be able to order a copy of this special issue.
In Section I (Earth), the poignant question “How Long Will the Earth remain Habitable?” was directed to David Catling at the University of Washington (WA).
As it ages, the sun is slowly brightening and in a few billion years, the Earth’s surface will be baked as our surface temperatures will soar over 1,000 degrees F.
Before this, the increasing temperatures will cause our oceans to evaporate, leading to reduced amounts of carbon dioxide. Photosynthesis, the process where plants take in carbon dioxide and exhale oxygen will cease.
In Section II (Planets Beyond our sun and Extraterrestrials), a question posed is “Which solar system ice worlds have oceans (below their surfaces)?”
Oceans means vast quantities of liquid water or brine. But if the outside temperature is far below freezing, then how can there be liquid water? The answer is internal heat, bottled up underneath their icy crusts.
This question was directed to Jeffrey Moore of the NASA/Ames (Iowa) Research Center. A moon long suspected of a thick subsurface ocean is Jupiter’s large moon Europa.
The Voyagers space probes and the Galileo Orbiter found Europa to have a cracked icy surface, resembling our Arctic ice packs. The Galileo probe measured the magnetic field about Europa, indicating an electrically conducting icy brine, likely 60 miles thick.
Saturn’s moon Enceladus erupts steam (H20) that contains organic compounds. Enceladus likely has large interior reservoirs of water. Cracks in the icy surface of Enceladus provide a passage way for heated water to escape. Under very low pressure, water boils at room temperature.
In Section III (Planets beyond our Sun and Extraterrestrials), the question “Can Planets Exchange Life?” was addressed to Selby Cull, a geologist at Bryn Mawr College (Philadelphia) and a member of an early NASA Martian landing team.
When a six-mile wide asteroid struck Central America (now Mexico’s Yucatan peninsula) 65 million years ago, the debris flung into the stratosphere caused the extinction of the dinosaurs.
But some rocks were hurled outward at many thousands of miles per hour, escaping the Earth’s gravity.
Some of these rocks eventually fell on Mars, Europa and perhaps Saturn’s big moon Titan. A rock at least 10 centimeter thick (four inches) could have carried Earth bacteria to other planets or to the large moons of the giant planets.
In Section IV (Stars, Supernovae and Black Holes), the question “Are Monster Black Holes travelling through the Universe?” was submitted to Marta Volonteri, of the Institut d’Astrophysique de Paris.
For decades, we have known that many galaxies, including our own Milky Way galaxy have massive black holes nested at their centers. But if two galaxies have a nearly head on collision, one of the central black holes may be ejected.
Marta comments that currently only one known galactic collision observed may led to the ejection of a monster black hole into intergalactic space.
In Section V (Galaxies and the Universe). The question “How Big is the Universe?” was tackled by Chris Impey, of the University of Arizona at Tucson.
We must first start with the estimated age of our universe of 13.74 billion years old. The farthest that light can travel in this time is 13.74 billion light years.
But during this vast amount of time, the matter emitting this early radiation has travelled several times farther away than this distance.
The consensus for the farthest distance detected by our most sensitive telescopes is 46 billion light years. So the known universe is 92 billion light years across. But this is the observable universe. The universe’s very small curvature suggests that the universe may be infinite!
SKY SIGHTS AHEAD: The evening of Aug. 20, the moon will be full, shining in front of the stars of Aquarius. This full moon of August will give us a preview of September’s Harvest Moon. Through Aug. 23, the moon will be rising in the early evening, great for moonlit strolls.
The brilliant planet Venus dominates the western sky at dusk, not setting until about 9:30 p.m. Late in the evening, the brilliant white-blue star Vega is nearly overhead.
Bob Doyle invites any readers comments and questions. E-mail him at firstname.lastname@example.org . He is available as a speaker on his column topics.