The Facts Nearly Everyone Gets Wrong About Pluto

Summary

In this engaging video, Alex McColgan of Astrum answers four of the most intriguing questions about Pluto. He explores why Hubble struggles to capture clear images of Pluto despite its ability to see distant galaxies, the nature of Pluto and Charon's unique orbital dynamics, the brightness of New Horizons' photos of Pluto despite its distance from the Sun, and the reason Pluto is no longer classified as a planet. The video also delves into the history of planetary classification, shedding light on Pluto’s status as a dwarf planet. A journey through Pluto’s mysteries, the video offers fascinating insights into our solar system.

Takeaways

• 😀 Pluto is a fascinating object in our solar system, often leaving viewers with many questions about its nature and characteristics.
• 🔭 Despite the Hubble Space Telescope’s ability to capture detailed images of distant galaxies, it struggles to capture clear images of small objects like Pluto due to its small angular diameter.
• 🌌 The size of celestial objects, like galaxies, plays a crucial role in how clearly they can be imaged, even from millions of light-years away.
• 🌑 Pluto is incredibly small in the sky—just 0.11 arcseconds across—making it hard to resolve in detail with telescopes like Hubble.
• 🚀 The 2015 New Horizons mission to Pluto provided the first detailed images of Pluto, offering groundbreaking insights into this distant dwarf planet.
• 🔄 Pluto and its moon Charon orbit a common point in space, known as a barycenter, which is located outside of Pluto due to their similar masses.
• 🌑 The phenomenon of Pluto and Charon orbiting a common center is also seen in the Sun-Jupiter system, where Jupiter's mass causes its barycenter to be outside the Sun.
• 💡 New Horizons' photos of Pluto appear bright, despite Pluto’s distance from the Sun, due to longer exposure times and the relatively bright 'Pluto time' on Earth.
• 💡 On Earth, 'Pluto time' occurs during dawn and dusk, providing a good visual representation of how bright Pluto can be at its high noon.
• 🌍 Pluto is no longer classified as a planet due to the International Astronomical Union’s updated definition, which requires a planet to have cleared its orbit of other objects.
• 🌌 The reclassification of Pluto as a dwarf planet is part of a broader effort to better categorize celestial objects, and has led to the promotion of other objects, like Ceres, to dwarf planet status.

Q & A

Why is Pluto so hard to see from Earth despite advanced telescopes like Hubble?

Pluto is extremely small in the sky, with an angular diameter of just 0.11 arcseconds at its closest approach. In comparison, distant galaxies like Andromeda are much larger in the sky, making them easier to capture even from great distances. This is due to the angular diameter, which refers to the apparent size of an object in the sky.

How can Hubble capture clear images of galaxies millions of light-years away, but struggle with Pluto?

Galaxies like Andromeda are much larger in size, despite being millions of light-years away, which makes them easier to resolve through Hubble’s imaging system. Pluto, being small in size and close to us, requires far higher resolution to capture any detailed images, which is why it’s hard to get clear shots of it from Earth-based telescopes.

Why does Pluto and its moon Charon orbit a point in empty space?

Pluto and Charon orbit around a barycenter, which is the center of mass between them. Since Pluto and Charon are almost equal in mass, their barycenter lies outside of Pluto itself, making it appear as though they orbit around an invisible point in space. This is also seen in the Sun-Jupiter system.

Why do New Horizons' images of Pluto appear so bright when it is so far from the Sun?

While Pluto is indeed dimmer than Earth due to its distance from the Sun, the images from New Horizons appear bright because of the long exposure times used during imaging. Additionally, the illumination on Pluto is similar to the low light levels we experience during dawn and dusk on Earth, which helps the spacecraft capture clear photos.

What is 'Pluto Time' and why is it important?

'Pluto Time' refers to moments on Earth when the illumination conditions resemble the sunlight on Pluto at noon. This occurs twice a day, at dawn and dusk, and gives us a sense of the light levels on Pluto, which are about 1/1600th of the sunlight we experience on Earth.

Why was Pluto originally classified as a planet?

Pluto was classified as a planet when it was discovered in 1930 because it was a large and distant object in our solar system. At that time, there were no clear distinctions between planets and other celestial bodies, which led to Pluto being placed in the planet category.

Why was Pluto demoted from being a planet?

In 2006, the International Astronomical Union (IAU) redefined the term 'planet,' introducing a new criterion: a planet must have cleared its orbit of other objects. Pluto, being in the Kuiper Belt with many similar objects, failed to meet this criterion and was reclassified as a dwarf planet.

What is the Kuiper Belt and how does it relate to Pluto?

The Kuiper Belt is a region beyond Neptune that contains many small, icy objects, including Pluto. As more objects like Eris, Haumea, and Makemake were discovered in this region, it became clear that Pluto was part of a class of objects rather than a unique planet.

How did the discovery of the Kuiper Belt affect Pluto's planetary status?

The discovery of the Kuiper Belt revealed that Pluto was not unique in its region of space, as it was one of many similar objects orbiting in the same area. This led to the realization that Pluto should be classified as a dwarf planet, rather than a full-fledged planet.

How did the mass of Pluto compare to that of the Moon, and why was this significant?

Pluto's mass is only about one-sixth of the Moon's, which led to complications in classifying it as a planet. The disparity between Pluto and the Moon in terms of mass highlighted the need for a clearer distinction between planets and smaller celestial objects.