Bob Doyle, Columnist
Early this year, I purchased the new Smithsonian atlas, “Universe — the Definite Visual Guide” published by Dorling-Kindersley.
The general editor is Martin Rees, Astronomer Royal of Great Britain. It’s ISBN number is 978-0-7566-9841-6.
Unlike most large format books, “Universe” has a number of instructive diagrams and insets on nearly all of its pages.
There are three main sections: First is the Introduction, which covers the key objects, processes, history of the universe and our view of the universe as seen from Earth.
This 74-page section is beautifully done and delivers a review of the science that has been used to understand the universe.
The second section is the Guide to the Universe, of over 200 pages, which gives you a tour of our solar system, our galaxy, the stellar zoo (the great variety of stars, live and dead that populate our galaxy) and the other galaxies and their groupings.
The third section is the Night Sky, recognizing the constellations and sights visible each month of the year, both from the Northern and Southern Hemispheres.
I can’t really cover all the key features of this 528-page book in one column, so I’ll describe some of the most interesting details from the Solar System portion from the second section, Guide to the Universe.
How was the solar system (sun and all the bodies that travel around it) formed? In “The History of the Solar System,” there is a fine sequence of diagrams explaining the nebular hypothesis of the French mathematician Pierre Laplace.
Not only did Laplace explain how the sun and planets formed, he also showed how the arrangement of planets would be stable, despite the planets pulling and tugging on each other.
The inner planets were blasted by the early sun, stripping them of much of their gases while the outer planets could continue to harvest gas and ice, growing to huge sizes.
Why do so many planets and moons have craters? Our Earth’s erosion and plate motions have obliterated most of our craters.
Craters are prominent on most moons, the planet Mercury and the asteroids. In the early solar system, many large pieces of debris collided with the planets and their moons, creating the craters.
Mercury rotates three times in two Mercury years. This causes its daylight period to last one Mercury year while the Mercurian nights are just as long.
The planet Venus’ axis is tipped over by 177.4 degrees. Our sister world rotates backward every 243 Earth days. Venus’ dense atmosphere circulates heat received from sun so well that there is only a few degrees difference at the surface between its poles and its equator.
Venus’ average surface temperature is 867 F, compared to 58 F for Earth.
Mars’ moon Phobos orbits only 5830 miles from Mars' surface. This moon is slowly spiraling in towards Mars.
When Phobos gets much closer to Mars, it will begin to break up due to tidal forces exerted by Mars.
Where is the biggest smog layer in the solar system? It’s not in Southern California!
The top layer of Saturn’s atmosphere absorbs the sun’s ultraviolet light. This combines with ammonia crystals to produce a smog layer that masks the colors of clouds in Saturn’s lower layers. Saturn’s diameter is over nine times as wide as the Earth.
Uranus’ thin rings were discovered in 1977 by an airborne observatory that was observing Uranus passing in front of a star. But five times before that event, the star’s light dimmed.
Then after Uranus had moved away from the star, there was a repeat of the same dimming pattern of the star’s light. This dimming was caused by Uranus’ five main rings.
Neptune and not Earth is the bluest planet. The eighth planet’s color is due to Methane in its atmosphere which absorbs the red and green of sunlight. The remaining blue light is reflected by Neptune’s clouds.
Pluto, now considered a dwarf planet is covered with ices of nitrogen, with traces of methane and carbon monoxide. This finding is from analysis of the light that Pluto reflects from the sun.
The most distant solar system object we know is Sedna, an object about one third the size of our moon. Sedna has a surface temperature of -436 F, making it the coldest known solar system body.
Sedna was discovered on the near side of its orbit. This ice world takes 11,400 years to orbit the sun.
SKY SIGHTS AHEAD: Tonight, a slim crescent moon should be visible low in the 9 p.m. western dusk. Near the moon will be the bright planet Jupiter. By next weekend, the moon will be half full (first quarter) and at its best for observing craters with binoculars.
The Cumberland Astronomy Club will meet May 17 at the LaVale Public Library at 7:30 p.m. The library is just off Route 40, about a mile to the east of the State Police barrack.
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.