Visual History of how we saw Pluto
How our understanding of Pluto has evolved over the years is fascinating. From being a only a dot visible to us, to a dot that bulges, to a clear color picture of the (dwarf) planet. Let us take you through its history visually.
Discovery in 1905–1930
The ninth planet (as known then) was discovered by Percival Lowell in 1905 from his personal observatory. Lowell initially kept it a secret so as to protect is pet project. He announced his “Planet X” only in 1908. Lowell predicted it to be much larger and the one to effect Neptune’s orbit. His search continued to 1915, but Pluto appeared only twice in the set of plates and was much dimmer than expected.
After Lowell’s death in 1916, not much moved till Clyde Tombaugh joined the Lowell observatory in 1929. He used a blink comparator to compare photographs and detect any movement which would betray the existence of a planet. On 18th February 1930, he was comparing two plates when he saw a star shifting position. Fainter than expected, he knew that he had finally found Lowell’s planet. It was finally announced on 13 March 1930, on Lowells birthday. After much drama, it was an 11-year old girl named Venetia Burney who suggested the name Pluto.
Not Much Visual Action in 40 years
Pluto was discovered to be within 6 degrees of position predicted by Lowell, but he pegged the size at being 6.6x of Earth. In 1955, it was determined by measuring brightness that Pluto has a period of rotation measuring 6.4 Earth days. In 1950, Gerard Kuiper used a 200-inch telescope to measure Pluto’s diameter to be 5,900km (Earth is 12,756km).
In 1976, Kitt Peak Observatory made near-infra red measurements that showed that Pluto was covered with frozen methane which is highly reflective. But, with that fact, the planet should appear much brighter. It was clear that Pluto was probably smaller than earlier assumed. In 1988, Pluto passed in front of a star which was its first occulation. The star did not wink out, it gradually disappeared and reappeared which meant that Pluto had an atmosphere.
Pluto is not alone
Many of Pluto’s photographs were elongated, which were believed to be defective. But, astronomer James Christy saw that the bulge moved around the planet. In fact, he showed that the bump progressed around Pluto in a 6-day period which established the satellite theory. The moon was named Charon.
Pluto becomes clearer — 1996 onwards
In the late 90’s, the Hubble telescope became operational. Now, astronomers could see Pluto without the interference of the Earth’s atmosphere. In 1996, first details of Pluto’s surface were revealed by Alan Stern and Marc Buie.
By 2006, Hubble also revealed that Charon was not the only moon. Pluto had two more companions named Nix and Hydra. And then, it spotted two more moons in 2011 and 2012 called Kerberos and Styx. Pluto was now a family.
The New Horizons Era — 2006 to 2015
Johns Hopkins APL took on an ambitious project. They engineered the New Horizons interplanetary space probe which was launched in 2006 with the primary mission to fly-by Pluto. It cruised passed Asteroids and Jupiter to reach Pluto Jan 2015.
The Surface Appears
After a scary software glitch, the spacecraft had its closest approach of the Pluto system on 14 July 2015, but the first data did not get to Earth till the next day. Download of the complete data set took 15 months though. That event gave us the breathtaking images of Pluto, its icy surface and its moons. Enjoy.
Pluto is mysterious. Get it on a Tee
Gazers.co has a great collections of space t-shirt, especially of Pluto. We use real imagery from real space crafts, space probes and telescopes to create our work. Hope you enjoy it.
