Stars & Planets
How are stars and planets different?
Stars
What are Stars?
Stars are giant spheres of superhot gas made up mostly of hydrogen and helium. Stars get so hot by burning hydrogen into helium in a process called nuclear fusion. This is what makes them so hot and bright. Our Sun is a star. Most of the pinpricks of light that shine in the night sky are also stars. Countless more stars are too far from Earth to be seen without a telescope. Most stars are incredibly far away.
Taken from Britannica and Ducksters
Studying Stars
The telescope was first built in the early 1600s by Galileo using glass lenses (this is called a refracting telescope). It had the magnification similar to our modern day binoculars, but allowed him to see the surface of the moon, several moons of Jupiter, and sunspots on the surface of the sun. Lenses have to be bigger to magnify more. However, the problem is that as glass lenses get bigger they get heavier and can distort the image. By the 1670s, Newton and Cassegrain invented a telescope using mirrors- the reflecting telescope. Both refracting and reflecting telescopes are called optical telescopes—they use visible light to make their magnifications.
The problem with land-based optical telescopes is that they also have to deal with distortions of light through the Earth’s atmosphere. The Hubble telescope was put in orbit around Earth (outside of the atmosphere) to solve this problem. Hubble is also an optical telescope (reflecting) that has provided some of the best pictures of space to us and furthered our understanding about things like star formation, black holes, and the origin of our universe.
Other types of telescopes using electromagnetic radiation other than visible light were invented in the 20th century. Today there are telescopes that use x-ray, infrared, radio, and gamma ray technology. These telescopes are able to detect things our human eye cannot see, such as high energy waves from black holes or exploding stars (gamma rays) and heat radiated from nebulae and galaxies (infrared). New technologies have drastically increased our understanding of space.
Planets
Our Solar System
The terrestrial planets are the first four planets in our solar system: Mercury, Venus, Earth, and Mars. They are small, rocky planets that are found between the sun and the asteroid belt.
The gas giants are the farthest four planets in our solar system: Jupiter, Saturn, Uranus, and Neptune. These planets are made up of gasses and are significantly larger than the terrestrial planets. These planets are located past the asteroid belt.
Here are some cool links to learn more about our solar system:
Stars & Planets in the Night Sky
Even though planets are far away in space, many of them are visible at night during certain times. Mercury, Venus, Mars, Jupiter, and Saturn are called the “bright planets” because they are the five brightest planets and can be seen with the human eye.
Over the course of days and weeks, these planets appear to change position against the starry sky, and they go through phases where they are visible from Earth. Their visibility is determined by the interaction of light from the sun and the planets’ own shadows. Sometimes these planets become visible just after it begins getting dark. Other times, they can only be seen very late at night. When they get too close to the sun, they aren’t visible at all. Since one or more of these planets may be hidden near the sun at any point in time, it may be several months before you can claim to have seen all of them.
How do you distinguish these planets from the stars?
- These planets are typically as bright as—or even brighter than—the brightest of stars!
- They tend to appear steady, whereas stars have a twinkling appearance.
- Since they are closer to the earth, you can see a disk rather than a tiny dot.
Taken from https://www.childrensmuseum.org/blog/why-can-i-see-some-planets-sky-and-not-others