Are we alone, or are "they" out there somewhere? While we can only guess how long humans have wondered about life beyond Earth, such curiosity surely predates recorded history.
In 1994, Terence Dickinson and Adolph Schaller published Extraterrestrials: A Field Guide for Earthlings which features amateur astronomer Dickinson's fascinating text and artist Schaller's dazzling illustrations.
After showing a sampling of Hollywood-created extraterrestrials (Mr. Spock, ET, and others) they conjecture about what real aliens might be like. Right off, Dickinson acknowledges that, paraphrasing earlier writers, extraterrestrials, if they exist, are apt to be not just stranger than we anticipated, but stranger than we could have anticipated. Still, he and Schaller make some intriguing speculations about such beings based on things we do know, like some basic laws of nature.
It is almost certain beings from other places would not resemble us. Just as we have been shaped by conditions on Earth, conditions where they live (temperature, gravity, atmospheric pressure and composition, amount and form of water, and the like) would have shaped their evolution.
Dickinson first looks at the kinds of places, in our solar system and beyond, where conditions might support life as we know and understand it. He discusses the evolution of brains and emergence of intelligence, and how smarter species are likely to out-survive the less smart ones.
He then examines, and Schaller visually portrays, the kinds of sensory organs aliens might use to gather information about their environment. Like humans, other life forms are likely to have mechanisms for sight, hearing, taste, smell, and touch.
They might have other sensory capabilities such as sonar (like bats and dolphins) or magnetic-field detection (like some birds, insects, and fish). Aliens might have "sight" in parts of the electromagnetic spectrum invisible to humans, enabling them to "see" ultraviolet, infrared, microwave, radio waves, x-ray, or gamma rays.
The authors pose one final mind-boggler. On Earth the chemical foundation of all life is carbon-based, but this might not be universal. Some life elsewhere might be silicon-based where crystalline critters nibble on rocks rather than bananas.
• Sky Calendar
*Aug. 13 Thu.: The Moon is at 3rd quarter.
*14 Fri. morning: The Moon passes through the Pleiades star cluster but moon glow will make binoculars needed to see the cluster.
*14 Fri.: Jupiter is at opposition, and thus at its best for the year.
*16 Sun. morning: The crescent Moon is to the lower left of Mars.
*17 Mon. evening: Saturn is to the upper right of brighter Mercury near the western horizon at dusk.
*20 Thu.: The Moon is new.
*22 Sat. evening: The crescent Moon is to the left of Mercury which is to the left of Saturn all near the western horizon at dusk.
*27 Thu.: The Moon is at 1st quarter.
• Perseid Meteor Shower. The best times for seeing Perseid meteors are Tuesday and Wednesday evening, August 11 and 12, until the Moon rises around midnight, but the nights before and after might also be worth a look. Perseus rises in the northeast but it's best to watch overhead where the sky is darkest.
• Naked-eye Planets. (The Sun, Moon, and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.) Evening: Saturn and Mercury are low in the west at dusk as Jupiter rises in the east. Morning: Jupiter is the brightest object in the southwest with "morning star" Venus in the east and much fainter Mars well above it.
Stargazer appears every other week. Paul Derrick is an amateur astronomer who lives in Waco. Contact him at 918 N. 30th, Waco, 76707, (254) 753-6920 or firstname.lastname@example.org. See the Stargazer Web site at stargazerpaul.com.