Key Takeaways About Whether the Sun is a Star or a Planet
- Is the sun a star or a planet? Modern definitions define a star as a body that generates its own energy. Although people have relied on the sun for hundreds of thousands of years, it is only in the last few centuries that science has agreed on its definition.
- Is the moon a planet or a star? Like the Sun, the Moon is not a planet, but a natural satellite.
- Modern technologies, such as advanced space telescopes, can help us redefine what solar objects are. Pluto, for example, was once considered a planet, but updated information changed the definition of what a planet is, and Pluto has since been demoted to a dwarf planet.
The sun is more than 4.5 billion years old, and early apes began living under its warmth more than two million years ago. How wise man They evolved to develop calendars based on sunlight, as well as the understanding that the Earth and Sun rotate.
But what exactly was it? It is only in the last few centuries that scientists have come to understand and agree on how to define the Sun and Moon. While these definitions are widely agreed upon, other solar objects have generated even more controversy.
Read more: If the color of the Sun is white, then why does it appear yellow?
What is the Sun?
Is the sun a planet? Star? Solar object?
“The sun is a star. The simple definition of a star is that the star produces its own energy,” says Michelle Nichols, astronomer and director of public observations at the Adler Planetarium in Chicago.
According to NASA, the Sun is made of hydrogen and helium and is the only star in our solar system. It is approximately 93 million miles from Earth, and its core temperature exceeds 27 million degrees Fahrenheit.
Although history is full of different names that different cultures have used to describe the Sun, naming and definition is now a matter for the International Astronomical Union (IAU).
“They have a lot of PhD astronomers who serve on various committees, and they are the ones who come up with these definitions,” Nichols says. “Science is constantly changing; classifications can also change.”
Is the Moon a planet or a star?
But the Moon is different. “The moon is a natural satellite,” Nichols says. “Our Moon is an object orbiting a planet. You may have natural satellites, but they don't necessarily orbit planets. An asteroid can have its own natural orbit.”
An artificial satellite is a solar object created by man and launched into space. Hubble Space TelescopeFor example, according to NASA, it is a low-orbiting telescope launched in 1990 that sends images of space back to Earth.
Satellites have also been launched into space for global communications and broadcasting. The number of these satellites has increased in recent years, causing some scientists to worry that they will spoil the images from the telescopes they rely on to learn more about our galaxy, according to a study published in the journal Natural astronomy.
Read more: Scientists are still pondering the mysteries of the Moon
Mapping the night sky
The IAU was founded in 1919, and one of its goals was to develop a standard for naming and classifying night sky objects. Until this point, Nichols said, different astronomers in different countries had their own names for the constellations.
“One astronomer would create a star map, and another astronomer would create his own. It was this mish-mash of maps and books and constellations,” Nichols says. “As we started to develop the capabilities of the telescope to find things that weren't obvious before, you have a need to classify things and give them names.”
After World War I, the IAU mapped the night sky using information available at the time. “They developed a standard list of 88 constellations that represent the entire sky,” Nichols says.
Definition of solar objects
But as telescopes became more sophisticated, astronomers were able to look further into our solar system, make comparisons, and question whether certain objects actually met the classification criteria.
“For decades we didn't have a definition of planets. We didn't need one. You had nine planets,” Nichols says. “Then, in the 1990s, they started finding objects beyond Pluto. When they found Eris, it turned out to be the same size as Pluto. The IAU came up with the definition of a planet. It turns out, as it was written, Pluto didn't meet all of those criteria.”
Pluto has been demoted to dwarf planet status. And while Nichols says there is no debate over the classification of the Sun and Moon, other solar objects are under scrutiny. For example, one of Pluto's five moons is called Charon, and is half the size Pluto.
“For something that's half the size of another, you're actually spinning around the center of mass, which is between the two objects,” Nichols says.
The definition of a planet could be written so that both Pluto and Charon are considered planets. At the moment, Pluto is a dwarf planet, and Charon is a natural satellite. But since the new powerful telescope Vera K. Rubin Observatory sends back never-before-seen images of the galaxy, scientists may discover new solar objects that will require them to rethink old definitions.
Read more: A new dwarf planet may appear in our solar system, orbiting even further than Pluto
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