Wando High School astronomy teacher Robbie Binnicker is a 2024 recipient of the state’s highest civilian honor, Order of the Palmetto, for his years as an educator. His physics and astronomy students may be the next generation of visionaries to shape NASA or SpaceX.

Trident Technical College astronomy professor Blake Crosby just returned from Chile, where he participated in a prestigious international astronomers’ program and observed the cosmos from stunning vantage points like a high plateau in the vast Atacama Desert.

Here, he answers some cosmic questions from Binnicker’s students:

Anna Mills: Do you consider Pluto a planet?

Crosby: Whether or not Pluto is a “planet” is inconsequential because it’s an interesting world either way.

When the 2015 New Horizons mission flew by Pluto, astronomers were shocked to find it is geologically active and even has a thin atmosphere.

Astronomers observe objects then group them based on shared characteristics. Ancient people didn’t initially know the difference between a planet and a star. However, they observed planets moved through the sky differently from stars, so they created a new type of object that had these characteristics. Mercury, Venus, Mars, Jupiter and Saturn were the original planets known to ancient observers. Uranus was discovered in 1781, Neptune in 1846. Pluto wasn’t discovered until 1930 and was famously demoted to dwarf planet in 2006.

Planets travel around the sun, have enough gravity to keep a spherical shape and clear orbits of most objects. Pluto failed the last requirement. Astronomers were finding many other quirky objects in the outer solar system. The International Astronomical Union categorized Pluto as a dwarf planet.

Categories are based on observable features, but it’s somewhat arbitrary where we draw the lines. 

Lincoln Thiem: What would happen if there was no magnetosphere?

(Editor’s note: NASA defines the magnetosphere as “the region around a planet dominated by the planet’s magnetic field. Other planets in our solar system have magnetospheres, but Earth has the strongest one of all the rocky planets: Earth’s magnetosphere is a vast, comet-shaped bubble, which has played a crucial role in our planet’s habitability. Life on Earth initially developed and continues to be sustained under the magnetosphere’s protection. The magnetosphere shields Earth from solar and cosmic particle radiation, and erosion of the atmosphere by solar wind which is what we call the constant flow of charged particles streaming off the sun.”) 

Crosby: Earth’s interior is hot. It is hot enough that the outer part of the core is liquid. As Earth rotates, the motion of electrically conducting fluid in the outer core generates magnetic field lines (the dynamo effect). These magnetic field lines surround the Earth and form the magnetosphere. This protective bubble shields Earth’s atmosphere from the solar wind, charged particles that stream away from the Sun. Without a magnetosphere to block the solar wind, our satellites and power grid would be at risk of damage from the charged particles. More importantly, Earth’s atmosphere would be slowly eroded away by the solar wind. Without an atmosphere, life would experience increased exposure to high-energy charged particles. The atmosphere is a protective blanket that helps the Earth retain its heat. Without it, the Earth would cool over time and become a cold, desert world. We don’t have to imagine this scenario; we just have to look at Mars, where it happened. Mars is smaller than Earth, so its interior cooled down faster. Therefore, it lost its dynamo and thus its magnetic field. The atmosphere was gradually lost through a combination of solar wind stripping and the planet’s weak gravity, leaving Mars as a cold, desert planet.

Preston Morse: Is the multiverse real? Is space finite?

(Editor’s note: The multiverse is a popular sci-fi plotline from the Star Trek franchise to the Marvel Cinematic Universe. It’s also hotly debated by physicists since the concept of multiple—or parallel— universes was proposed by physicist Hugh Everett III in 1957.) 

Crosby: Some scientific theories suggest our universe might be just one of many. These other universes could have different properties or even different laws of physics.

However, and this is very important: We have no direct evidence that other universes exist. So right now, the multiverse is an interesting idea, not something we’ve confirmed.

Now, is space infinite? We’re not sure. There are two main possibilities: space goes on forever (infinite), or space is finite but has no edge, like the surface of a sphere (if you keep going, you eventually loop back). Observations show the universe is very close to what we call ‘flat,’ which means it could be infinite, or just so huge we can’t tell.