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Pluto

Short answer: Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory, and it was counted as the ninth planet until August 24, 2006, when the International Astronomical Union defined 'planet' in a way that made Pluto a dwarf planet.

NASA's New Horizons flew past in July 2015 and photographed a bright, heart-shaped region named Tombaugh Regio after its discoverer. The heart's western lobe, Sputnik Planitia, is a vast basin of nitrogen, carbon monoxide and methane ices; the eastern lobe is uplands coated with nitrogen ice. The footage shows New Horizons images of Pluto, the observatory dome and icy terrain, with the presenter.

VideoWrite-up3 sources
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What should you know about Pluto?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Pluto was reclassified as a dwarf planet in 2006.

    DD-125-F01 · Write-up · Exhibit B (Dwarf planet)

  2. Pluto's heart is named Tombaugh Regio.

    DD-125-F02 · Write-up · Exhibit D (Tombaugh Regio)

Video transcript: Pluto: Pluto Has a Heart Made of Ice

Pluto once considered the ninth planet in our solar system, was reclassified as a dwarf planet by the International Astronomical Union in 2006. DID YOU KNOW? Despite its diminutive size, Pluto has a heart-shaped feature on its surface officially named Tombaugh Regio after Clyde Tombaugh, who discovered Pluto in 1930. This heart-shaped region also known as Pluto's heart or love is a large plain of nitrogen and other ices. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 23.8s Reel ·

Video coming soonPluto · Instagram Reel
Pluto: Pluto Has a Heart Made of Ice Instagram Reel · · 23.8s

The write-up

Pluto has a heart made of ice. The IAU reclassified Pluto as a dwarf planet on August 24, 2006.

  1. Exhibit A

    Found in 1930

    Clyde Tombaugh discovered Pluto in 1930.

  2. Exhibit B

    Dwarf planet

    The IAU reclassified Pluto as a dwarf planet in 2006.

  3. Exhibit C

    New Horizons

    NASA's New Horizons flew past Pluto in July 2015.

  4. Exhibit D

    Tombaugh Regio

    Pluto's heart-shaped region is named after Tombaugh.

  5. Exhibit E

    Sputnik Planitia

    The heart's western lobe is a basin of nitrogen and other ices.

Questions people ask about Pluto

Who discovered Pluto?

In 1930.

Source: Write-up · Exhibit A (Found in 1930) · NASA Science: Pluto; Wikipedia: Pluto

When was Pluto reclassified?

By the IAU.

Source: Write-up · Exhibit B (Dwarf planet) · NASA Science: Pluto; Wikipedia: Pluto

Which spacecraft flew past Pluto?

In July 2015.

Source: Write-up · Exhibit C (New Horizons) · NASA Science: Pluto

What is Pluto's heart called?

It honors its discoverer.

Source: Write-up · Exhibit D (Tombaugh Regio) · Wikipedia: Tombaugh Regio

What is Sputnik Planitia made of?

It's the heart's western lobe.

Source: Write-up · Exhibit E (Sputnik Planitia) · Wikipedia: Tombaugh Regio

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. Who discovered Pluto?

    1. Clyde Tombaugh
    2. Percival Lowell
    3. Carl Sagan
    4. Edwin Hubble
    Show the answer

    Answer: A. Clyde Tombaugh In 1930. Source: Write-up · Exhibit A (Found in 1930) · NASA Science: Pluto; Wikipedia: Pluto

  2. When was Pluto reclassified?

    1. 2006
    2. 1930
    3. 2015
    4. 1999
    Show the answer

    Answer: A. 2006 By the IAU. Source: Write-up · Exhibit B (Dwarf planet) · NASA Science: Pluto; Wikipedia: Pluto

  3. Which spacecraft flew past Pluto?

    1. New Horizons
    2. Voyager 1
    3. Cassini
    4. Juno
    Show the answer

    Answer: A. New Horizons In July 2015. Source: Write-up · Exhibit C (New Horizons) · NASA Science: Pluto

  4. What is Pluto's heart called?

    1. Tombaugh Regio
    2. Sputnik Crater
    3. Lowell Plain
    4. Charon Basin
    Show the answer

    Answer: A. Tombaugh Regio It honors its discoverer. Source: Write-up · Exhibit D (Tombaugh Regio) · Wikipedia: Tombaugh Regio

  5. What is Sputnik Planitia made of?

    1. Nitrogen and other ices
    2. Lava
    3. Sand
    4. Liquid water
    Show the answer

    Answer: A. Nitrogen and other ices It's the heart's western lobe. Source: Write-up · Exhibit E (Sputnik Planitia) · Wikipedia: Tombaugh Regio

Cite this case file

Easterling, Marcus. "Pluto." The Detail Department (DetailEnjoyer), case file DD-125, last updated Dec 16, 2023. https://detailenjoyer.com/case/pluto/

Permalink: https://detailenjoyer.com/case/pluto/ · Last updated

Markdown version

Cite a single fact by its ID, for example DD-125-F01 → https://detailenjoyer.com/case/pluto/#DD-125-F01