May 25, 2020

2015: The Year We See Pluto Up Close

An artist’s conception of New Horizons at Pluto. Credit: NASA.

The late American astronomer Clyde Tombaugh got a birthday present yesterday when NASA’s New Horizons spacecraft released an image of Pluto and its moon Charon.

Born in 1906, Mr. Tombaugh would’ve been 109 this year. And although yesterday’s image snapped by New Horizon’s LORRI navigational camera wasn’t a spectacular one, expect that to improve drastically as the NASA spacecraft heads towards its historic July encounter.

A comparison of a recent image of Pluto and Charon snapped by New Horizons (right) and a simulated view. Credit: Starry Night Education software and NASA/New Horizons.

“This is our birthday tribute to Professor Tombaugh and the Tombaugh family, in honor of his discovery and life achievements – which truly became a harbinger of 21st century planetary astronomy,” said New Horizons principal investigator Alan Stern in a recent press release.

An animation showing the orbit of Pluto’s moon, Charon. Credit: NASA/JHUAPL/SwRI.

New Horizons was launched atop an Atlas V rocket from Cape Canaveral, Florida on 2006. New Horizons was reawakened permanently for this year’s encounter on December 6th, 2014, and will fly 10,000 kilometres from Pluto on July 14th. Currently closing in on Pluto at a blazing 14 kilometres per second, the Pluto New Horizons encounter is THE big ticket event in space exploration this year. Currently about 3 pixels across, images of Pluto and Charon taken by New Horizons now exceed those taken by the Hubble Space Telescope.

Currently still 1.26 astronomical units from New Horizons, Pluto currently hovers around +7th magnitude in brightness, with +9th magnitude Charon sitting 20” off its limb. The LORRI images also serve a scientific purpose as well, as engineers are currently imaging Pluto against the background stars to refine our understanding of the positions of New Horizons with respect to Pluto and its five moons during the July encounter.

New Horizons is unable to put on the brakes and enter orbit around Pluto, as a high speed trajectory was necessary to get it there within a decade. The next few months will see a flurry of activity, as New Horizons puts a face on these brave new worlds. From there, New Horizons now has a short-list selection of Kuiper Belt objects for exploration in the coming decade before it joins the two each Pioneer and Voyager spacecraft orbiting the galactic disk.















The blink comparator that Clyde Tombaugh used to discover Pluto on display at the Lowell Observatory. Photo by author.

New Horizons carries a Florida state quarter, a US Flag, a piece of Scaled Composites SpaceShipOne, and a disc with the names of nearly half a million supporters, along with the cremated remains of Pluto discoverer Clyde Tombaugh, who passed away in 1997. New Horizons also carries among its suite of instruments the Venetia Burney Student Dust Counter, named after Venetia Burney, (later Venetia Phair) the girl who named Pluto at age 6 shortly after its discovery in 1930. Miss Phair died in 2009.















New Horizons in the clean room. Credit: NASA.

What will Pluto look like? Does it have rings or undiscovered moons? Is Pluto a planet, or the “King of the Kuiper Belt Objects?” There’s some thought that Pluto may resemble Triton, Neptune’s largest Moon. There’ll certainly be a flood of new surface features awaiting names on Pluto and its moons, as the map of these worlds gets fleshed out. Certainly, Miss Phair and Mr. Tombaugh deserve their due, and we’ve proposed the mythological name ‘Alecto’ with a ‘CT’ spelling as a tribute to Clyde Tombaugh.

Pluto also just passed solar conjunction as seen from the Earth on January 3rd, and reaches opposition on July 6th in the constellation Sagittarius just a week prior to the New Horizons encounter. At +14th magnitude, Pluto is a tough target for even a large telescope, though you can actually ‘wave’ in the direction of Pluto and New Horizons on the morning of February 15th using the nearby waning crescent Moon as a guide:















Looking to the SW on February 15th about an hour before dawn. Credit: Stellarium.

It’s going to be a great year for space exploration!

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