Exoplanets are a niche topic for many people, rarely brought to mind except to note an occasional discovery before moving on to the rest of the day’s news. But Gliese 581 c is causing ripples. Yesterday, BBC radio host Eddie Mair referred to it as ‘the planet everyone is talking about.’ And last night on my regular walk I passed a neighbor I run into almost every evening. He was standing in his yard looking west under a sky dominated by an incredibly bright Venus. This is a man I have known for years, and not once in that time have we spoken about astronomy. But on this night, he said “So how do you pronounce G-l-i-e-s-e?”
I’ve always said ‘Glee-see,’ but as astronomer Wilhelm Gliese was German, the proper way to say it really should be ‘Glee-zuh’. Gliese (1915-1993) first came to my attention about twenty years ago when I was trying to work out the odds of picking up accidental radio emissions from civilizations near the Sun. The Gliese Catalog of Nearby Stars told me what was where, all known stars within 25 parsecs of the Sun.
That seemed pretty esoteric too, but this morning I passed another neighbor (I walk a lot, usually three or four miles a day). The sky was soft, tawny, criss-crossed with contrails and promising rain by evening. We exchanged pleasantries and talked about the new planet. What got her going was my use of the word ‘nearby.’ “You say it’s a nearby star. How long would it take to get there?” I told her 20 years if we could move at the speed of light and her eyes widened. “If that’s nearby,” she said, “I’d hate to know what you consider far away!” We both laughed and looked into the sky, shaking our heads at the sheer scale of things.
Maybe I’ve coined a new term — a ‘Gliese moment’ — that describes what happens when a formerly niche topic suddenly goes mainstream. In any case, what an opportunity to get people not normally involved with astronomy to acquaint themselves with what the exoplanet hunt is really about. This past decade of ‘hot Jupiters’ and outer system giants is giving way to a period when planets not much larger than ours will be swimming into view. Give us another decade and we may be looking at reflected light off a planet with an atmosphere, oceans and clear signs of life.
My unexpected conversations on this topic have completely delighted me. Because what I am picking up is the palpable sense of awe as people leave their daily concerns behind for a moment and start to think about just how big the universe is, where we might fit in it, and what else we might find as we push ever further out toward stars like Gliese 581. This new world was like finding an unexpected gift at the door, one that made these two people, both nearing retirement, feel enchanted with the cosmos again. As for me, Gliese 581 c, that distant world under a dim red sun, warm in places and maybe water-laden, has put a definite spring in my step. The hunt for terrestrial exoplanets has only begun.