Lyceum B - Astronomy - Week 34 - Pluto
- Jul 6, 2022
- 4 min read
Updated: Jul 6, 2022
Pluto is located in the Kuiper belt, a ring of astronomical bodies beyond the orbit of Neptune.
Pluto has 5 known moons.
Pluto was once considered the 9th planet, but there have now been several other bodies of similar size discovered in the Kuiper belt, including the dwarf planet, Eris. Because of this, since 2006, it has officially been downgraded to a dwarf planet.
From wiki:
Pluto is the largest known trans-Neptunian object by volume, but is less massive than Eris. Like other Kuiper Belt Objects, Pluto is primarily made of ice and rock and is relatively small - one-sixth the mass of the Moon and one-third its volume. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units or AU from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, but a stable orbital resonance with Neptune prevents them from colliding.
—————————————
AU is a unit of length = the distance of Earth from the Sun
——————————————————
Pluto was discovered in 1930 by American astronomer, Clyde Tombaugh, who had been hired by the Lowell Observatory in Arizona for that purpose.
From space.com:
American astronomer, Percival Lowell, first caught hints of Pluto’s existence in 1905 from odd deviations he observed in the orbits of Neptune and Uranus, suggesting that another world’s gravity was tugging at these two planets from beyond. Lowell predicted the mystery planet’s location in 1915, but died without finding it.
From wiki:
Tombaugh’s task was to systematically image the night sky in pairs of photographs, then examine each pair and determine whether any objects had shifted position. Using a blink comparator, he rapidly shifted back and forth between views of each of the plates to create the illusion of movement of any objects that had changed position or appearance between photographs. On February 18, 1930, after nearly a year of searching, Tombaugh discovered a possible moving object on photographic plates taken on January 23 and 29. A lesser-quality photograph taken on January 21 helped confirm the movement. After the observatory obtained further confirmatory photographs, news of the discovery was telegraphed to the Harvard College Observatory on March 13, 1930.
From space.com:
Pluto got its name from 11-year-old Venetia Burney of Oxford, England, who suggested to her grandfather that the new world get its name from the Roman god of the underworld. Her grandfather then passed the name on to Lowell Observatory. The name also honors Percival Lowell, whose initials are the first two letters of Pluto.
Observations of Pluto’s surface by the New Horizons spacecraft revealed a variety of surface features, including mountains that reach as high as 11,000 feet (3,500 meters), comparable to the Rocky Mountains on Earth. While methane and nitrogen ice cover much of the surface of Pluto, these materials are not strong enough to support such enormous peaks, so scientists suspect that the mountains are formed on a bedrock of water ice.
——————————————————
Project - Make a Blink Comparator
From How the Universe Works:
Clyde Tombaugh discovered Pluto using a blink comparator, an instrument that enables you to compare two photographs of the same part of the sky taken at different times. Any small difference between the two photographs can be quickly discovered, even when there are tens of thousands of stars in a photograph.
The images are inspected through the same viewing eyepiece and lit one after the other, changing once a second. Any object that is on only one of the photographs seems to “blink” on and off. A planet changes its position between one photograph and the other and looks as if it were jumping forward and backward.
Need a box measuring about 8 x 12 inches, 2 small sheets of acrylic plastic, tracing paper, thick tape, like electrical tape, 2 flashlights and a protractor.
Cut 2 slots in the top of the box at 45° to the sides. Cut 3 holes in the sides of the box. There will be one hole on 3 different sides of the box each measuring 2 in x 2 inches.
Draw two 2 x 2 inch squares on tracing paper. Add a pattern of stars and a cross to one square, In the other square piece of tracing paper, copy the same pattern, but move the cross slightly to one side.
Glue the tracing paper to the two squares on opposite sides of the box so that the patterns face outward.
Cover the edges of the acrylic plastic with thick tape so you won’t cut yourself on the sharp edges. Insert the plastic sheets into the slots you cut.
Shine each of the flashlights onto the sheets of tracing paper.
Look through the viewing hole and make any needed adjustments so that the star patterns line up perfectly. (You may need to adjust the position of the acrylic sheets very slightly to aid in lining up the two images of stars.
Now look through the viewer again while someone else flashes the flashlights on and off quickly.
Do you see any movement?
-------------------------------
Videos:
Professor Dave Explains
Edwin Hubble, Doppler Shift, and the Expanding Universe - 8:10 min
Crash Course Astronomy #24
Light - 10:33 min
Comments