Lucy Bennison Laffitte, MEd, PhD
Executive Committee, International Big History Association
North Carolina, USA
People have been pondering other worlds since we first crawled down from the trees onto the grasslands and looked up at the night sky. Watching the nightly rising and setting of stars, monthly changes of the moon, periodic meteor showers, yearly shifts in the constellations, and the curiously wandering stars, it’s easy to imagine that even the most ancient of people yearned for communion with other celestial life. It’s a uniquely human urge.
A quick jump through the last 5,000 years of astronomy’s history demonstrates how the instruments and insights of the discipline have evolved as technology has developed and collective learning increased.
- In ancient Babylonia, astronomers recorded the rise and set of the planets and unusual events like Haley’s comet on cuneiform tablets. They also divided the firmament into 360 degrees for tracking planets in space.
- In ancient Greece, astronomers named the constellations, and marked the ecliptic with the zodiac. They also measured and mapped the location of stars using sextants and parallax (BHP students can learn to measure distances using parallax in Lesson 1.4).
- In Enlightenment Europe, astronomers used optical telescopes to find moons around planets to bolster the idea that the Earth revolved around the Sun.
- During the Industrial Revolution, astronomers used spectroscopes to analyze the spectrum of light from distant objects. The spectral absorption and emission lines provided the evidence to determine which elements other planets and stars were made of.
- In the Information Age, we are building telescopes of all sizes to capture the data from all wavelengths of the electromagnetic spectrum. Infrared telescopes, when put into orbit above the Earth’s atmosphere, are able to measure the transit and radial velocity of tiny planets as they pass through the habitable zones around the suns of other solar systems.
The discovery of Proxima Centauri B this summer has energized those thinking about finding extraterrestrial life. The planet orbits Proxima Centauri, the closest star to our Sun, which is only 4.2 light years from Earth. It has a temperature range that would make liquid water possible. But the likelihood of finding life there diminishes when you consider the other details of this planet.
Proxima Centauri is a small red dwarf star only one-eighth the size of our Sun. The planet Proxima B is similar to Earth in size, but has a drastically short year—11 days long. And it orbits very close to its sun. The Earth is 20 times farther from our Sun as Proxima B is from Centauri. The solar wind coming off Centauri is predicted to be 2,000 times stronger than what Earth experiences, and we have a magnetic shield.
The exoplanet community is not deterred by this, however. They hope to send robots to the surface, anticipating the thrill of understanding another planet outside of our Solar System. Proxima Centauri B may not be a world ready to receive text messages and emoticons, but a visit there will no doubt aid us in our quest to find a planet that is.
About the author: Lucy Bennison Laffitte, MEd, PhD, has been teaching science in-context for over 30 years. She currently teaches Big History through the Honors College at North Carolina State University and in the Summer Accelerator Program for the North Carolina School of Science and Math. Lucy has published in print, on air, and on the web—authoring a newspaper column, founding an award-winning environmental radio program, creating certificate programs, and developing digital learning objects for public television.