Observation and the new planets next door
The discovery of a whole family of new-to-us planets is a reminder how observatories have evolved over time.
This illustration provided by NASA/JPL-Caltech shows an artist's conception of what the TRAPPIST-1 planetary system may look like, based on available data about their diameters, masses and distances from the host star. The planets circle tightly around a dim dwarf star called Trappist-1, barely the size of Jupiter. Three are in the so-called habitable zone, where liquid water and, possibly life, might exist. The others are right on the doorstep.
NASA/JPL-Caltech/AP
The discovery of seven “Earth-like” (loosely speaking) planets orbiting a star a mere 39 light-years away must be, in astronomical terms, equivalent to a 5-year-old’s excited discovery that the family moving in next door has several children: “There’s got to be at least one for me to play with!”
The news broke the other week as I was returning from a family trip that had already left me with things astronomical on my mind: Our outing included a buzz around the Griffith Observatory in Los Angeles.
How have observatories changed over time?
European scientists had been tracking TRAPPIST-1, the ultra-cool dwarf star at the center of the newly discovered solar system, since late 2015. They used, first, the European Southern Observatory’s Transiting Planets and Planetesimals Small Telescope-South (whence “TRAPPIST”) and later, ESO’s prosaically named Very Large Telescope, in the remote Atacama Desert of northern Chile. Finally, the Spitzer Space Telescope afforded good views of the “new” planets transiting their star.
The Griffith, meanwhile, is a very different observatory. Open to the public, it was a gift from the redundantly named Col. Griffith J. Griffith in 1935. It offers a clear view of the famous Hollywood sign and has a list of film and TV credits that would do any A-list star proud, including the current “La La Land.”
Observatory came into English from the French observatoire to refer to the Royal Observatory at Greenwich, outside London. It was founded in 1675 by King Charles II “specifically to solve the problem of finding longitude while at sea,” the Online Etymology Dictionary says.
The astronomical sense of observatory remains primary, but some observatories gather other kinds of data: the Hawaiian Volcano Observatory, for instance, which marked its centennial in 2012. NASA’s Airborne Snow Observatory has been tracking the snowpack in California. More broadly, the Syrian Observatory for Human Rights, which The New York Times calls “virtually a one-man band,” tracks data on casualties in Syria’s civil war. A Monitor story on secularism in France a few months ago cited another soft-science “observatory,” the Observatory for Religion in the Workplace.
Observe, as a verb, comes from Latin roots meaning “to serve” and “before” or “in front of.” It originally meant “to keep” or “hold to.” To “observe” a stop sign, in this sense, means not just to notice it but actually to stop.
Later the word meant to protect or keep safe. The biblical reference to Herod “observing” John the Baptist (see Mark 6:20) may suggest to moderns that the king had the prophet under surveillance. But in fact the word suggested protection.
The “scientific” sense of observe – “watch, perceive, notice” – came later, around the middle of the 16th century. This was just as great early astronomers were coming on the scene – men like Johannes Kepler, whose brilliant discovery that planetary orbits are elliptical, not circular, still helps scientists today as they calculate the courses of distant planets.