Beyond E.T.

The breathtaking conjunction of Venus and Jupiter in the northern hemisphere this month has turned many heads skyward. Yes, the December sky has been a treasure trove of jewels for amateur astronomers, featuring ancient constellations such as Triangulum and Cassiopeia, and a full moon on December 12 that was its closest to Earth since 1993.

Even more captivating were the first published photographs on November 13 of exoplanets—planets outside our own solar system.

For many, the interest in exploring beyond our solar system is limited to the search for little green men. The idea of intelligent civilizations in the universe, maybe even in our own galaxy, holds an obvious fascination.

It certainly did for me. As a little girl, classic movies such as The Day the Earth Stood Still and books such as Douglas Adams’ The Hitchhiker’s Guide to the Galaxy dominated my imagination. I was determined to be like Eleanor Arroway in Carl Sagan’s book Contact, an astronomer for the Search for Extraterrestrial Intelligence (SETI) Institute.

However, the discovery of 331 exoplanets during the last 20 years—and especially the recent photographic proof of four of those—is monumental beyond the search for E.T.

Planets within our solar system—from the rocky inner planets to the outer gas giants to the dwarf planet Pluto—maintain their mystery. Scientists have long theorized about the origins of the planets, their relationships with each other and with the sun. Yet, we don’t really know what our solar system was like in its infancy. At 5 billion years old, the sun is now about halfway through its life. But what was our solar system like at 200 million years old? And what will our solar system look like when our sun dies?

To answer those questions, scientists have looked beyond our solar system. Prior to the published photographs, they detected exoplanets using indirect methods, including astrometry (studying the wobble of a star created by the gravitational pull of a planet), transit method (when a planet passes in front of a star and the star’s light dims) and, occasionally, gravitational lensing (observing light from distant sources bending around the mass of a closer object).

Yet the photographs published of Fomalhaut and its orbiting planet Fomalhaut b, as well as the three-planet system of HR8799, allow scientists to directly observe, for the first time, solar systems at different stages of development.

All four photographed planets, as well as the nearly 300 other exoplanets, are uninhabitable gas giants like Jupiter. The planets orbiting HR8799 are seven to 10 times larger than Jupiter. The simple reason is that larger, brighter planets are easier to detect at such great distances.

Ultimately, what’s just happened is the first step toward discovering terrestrial planets and an entire system that’s much like our own. And maybe I can still reserve a little hope for becoming like Eleanor Arroway and finding another pale blue dot in the Goldilocks Zone—that distance from a star that’s not too hot and not too cold, but just right … for life.