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[...] Review: How to Build a Habitable Planet by James Kasting. : Astro Guyz [...]
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Pictured is a Delta IV rocket launch from Cape Canaveral on November 21st, 2010. The image is a 20 second exposure taken at dusk, shot from about 100 miles west of the launch site. The launch placed a classified payload in orbit for the United States Air Force.
Difficult but not impossible to catch against the dawn or dusk sky, spotting an extreme crescent moon can be a challenge. The slender crescent pictured was shot 30 minutes before sunrise when the Moon was less than 20 hours away from New. A true feat of visual athletics to catch, a good pair of binoculars or a well aimed wide field telescopic view can help with the hunt.
The Sun is our nearest star, and goes through an 11-year cycle of activity. This image was taken via a properly filtered telescope, and shows the Sun as it appeared during its last maximum peak in 2003. This was during solar cycle #23, a period during which the Sun hurled several large flares Earthward. The next solar cycle is due to peak around 2013-14.
Located in the belt of the constellation Orion, Messier 42, also known as the Orion Nebula is one of the finest deep sky objects in the northern hemisphere sky. Just visible as a faint smudge to the naked eye on a clear dark night, the Orion Nebula is a sure star party favorite, as it shows tendrils of gas contrasted with bright stars. M42 is a large stellar nursery, a star forming region about 1,000 light years distant.
Orbiting the planet in Low Earth Orbit (LEO) every 90 minutes, many people fail to realize that you can see the International Space Station (ISS) from most of the planet on a near-weekly basis. In fact, the ISS has been known to make up to four visible passes over the same location in one night. The image pictured is from the Fourth of July, 2011 and is a 20 second exposure of a bright ISS pass.
Next to the Sun, the two brightest objects in the sky are the Moon and the planet Venus. In fact, when Venus is favorably placed next to the Moon, it might just be possible to spot the two in the daytime. Another intriguing effect known as earthshine or ashen light is also seen in the image on the night side of the Moon; this is caused by sunlight reflected back off of the Earth towards our only satellite.
A mosaic of three images taken during the total lunar eclipse of December 21st, 2010. The eclipse occurred the same day as the winter solstice. The curve and size of the Earth’s shadow is apparent in the image.
The Algonquin Indians had names for each of the seasonal Full Moons, many of which survive today. The Full Snow Moon pictured occurs in the month of December, when the first large winter storms coat the ground with snow. This Full Moon also tends to fall near the Winter Solstice, and thus rides high in the nightly sky opposite to the Sun on long winter nights.
Every rocket launch is unique, but twilight shuttle launches where by far the most impressive. The image pictured was of the April 5th, 2010 launch of Space Shuttle Discovery from the Kennedy Space Center at dawn. The exhaust plume caught the rising Sun overhead just right, and numerous noctilucent clouds persisted right up until sunrise. Unfortunately, space shuttle launches are now relegated to the pages of history.
Review: How to Build a Habitable Planet by James Kasting.
Some years ago, a book entitled Rare Earth was published amid much controversy. The central thesis of this work was that events that led to the eventual habitability and diversity of life and intelligence on Earth were so improbable, as be near to impossible to replicate elsewhere in our galaxy. The book marked a sort of change in thinking in the realm of exobiology, one from “intelligent civilizations are everywhere” championed by the late Carl Sagan to the concept that we may be the only ones, if not the first.
As the science fiction writer Arthur C. Clarke once said, either idea has stunning consequences…
Now, another such shift in thinking is underway again. This is heralded by the book How to Build a Habitable Planet by James Kasting and out by Princeton Press. Mr. Kasting is a considerable authority on the subject. A Distinguished Professor of Geosciences at Pennsylvania State University, he is actively involved with NASA in the search for Earth-like worlds. The book pulls together all of the latest research to paint a picture of how our planet formed and became a stable haven for life as we know it. Kasting serves up the examples of our nearest planetary neighbors skirting the habitable zone of our solar system, as Mars and Venus get a chapter each. We’ve always thought that it was fortuitous that we have two good studies in comparative planetary science in our solar system. Venus, about the size of the Earth, shows us how things might be without liquid water closer in to the Sun, and Mars shows us how life would be at a tinier size and without a magnetic field. The author also tackles the “faint sun paradox;” It is known that the Sun was appreciably dimmer earlier in its history; how then, did we avoid a scenario of a “snowball Earth?” The author backs up the discussion with hard data throughout. Other puzzles are tackled, such as the source of the Earth’s oceans and the secret life of methagens in the early history of life on our planet.
Approaching Venus.
The author also takes the dilemma of the Rare Earth Hypothesis head-on and intelligently addresses the pros and cons of the issue. The author is wise to point out that it is simply too early in our search to definitively shout out “We are alone!” Right now, we can only base this conclusion on a biosphere sample of one; discovery of even ancient microbial life elsewhere in our own solar system would have immense repercussions for the search for life elsewhere, as well as narrow in on a key parameter of the Drake Equation…
And speaking of which, the author devotes the last half of the book to the search for extra-solar planets. Currently the hottest field in astronomy today, discoveries are coming in at a fast and furious rate. The refinement in techniques and technologies are leading up to a tantalizing goal; the imaging of an Earth-like world. If a spectrum can be obtained, key signatures could be ferreted out. Markers such as methane, water vapor, and free O2 and O3 may be clues that something biologically interesting is taking place on a far off world. The author covers current search methods of radial spectroscopy and catching exoplanet transits and touches on the future promises of such missions as the Kepler Space Telescope, ESAs Gaia, and the Terrestrial Planet Finder series. Farther on down the road, the author envisions such intriguing concepts as the Exo-Earth Detector, a constellation of free flying telescopes that could form one giant hyper-telescope. Other mind-bending ideas include placing a telescope at a distance of 600 A.U. and using our own Sun as a giant gravitational lens. Or how about actually targeting an exo-Earth in our galactic neighborhood with a probe propelled by a solar sail driven by a Moon- or space-based laser? The author points out that such a device was depicted in Larry Niven’s The Mote in God’s Eye, and would have the advantage of not having to carry its own inertia-filled fuel…
The Dunes of Mars. (Credit: NASA/HiRise/JPL).
Read How to Build a Habitable Planet to get a fascinating look at our evolving understanding of how our Earth came to be, and our efforts to define our place in the cosmos. We may not be rare, but the Earth from our vantage point is truly a special place, and our home. And one day we hope to have background of an Exo-Earth adorning our laptop!
The exoplanet hunters…the mirror segments of the future James Webb Space Telescope. (Credit Ball Aerospace).