Tag: thermonuclear fusion

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Wandering Stars in the Sky

"Wandering Stars" in the Sky

The ancient Greeks saw the five visible planets and called them “wandering stars” because they moved randomly across the sky instead of staying in fixed positions like the stars. The word “planet” comes from the Greek word for “wanderer.”

We have known for many centuries that the planets are not stars. They appear to wander because they orbit the Sun, just like our planet Earth. They orbit at different speeds, making them appear to wander in the sky. For astronomers to classify a celestial body as a planet, it must meet three requirements:

  1. It must have enough mass for gravity to cause it to become spherical, unlike an asteroid.
  2. It must not have enough mass to cause thermonuclear fusion, which would make it a star.
  3. It must have cleared the area of debris known as planetesimals.

We have five planets that are visible without the aid of telescopes or even binoculars. Two of the visible planets are called inferior planets, not because of importance but because their orbit is inside Earth’s orbit. They are Mercury and Venus. The other three are known as the superior planets since they are beyond Earth’s orbit. They are Mars, Jupiter, and Saturn.

There is one essential thing the ancient Greeks did not understand about the solar system. They did not know that it is orderly. The Greeks saw a pantheon of gods controlling various aspects of the Earth and skies. Each of their gods had all of the bad traits of humans struggling with each other. It was the Judeo-Christian concept of one almighty and wise creator God who created an orderly system that led to the scientific understanding of the cosmos.

Today, we can study and understand the wisdom of God in creation. Because of that, we can know where the planets and stars, as well as solar and lunar eclipses, will be visible at any given time and from any location on Earth. Those “wandering stars” are not wandering after all.

— Roland Earnst © 2020

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Interesting Sun Facts

Interesting Sun FactsWe all know some things about the Sun. We know it is powered by thermonuclear fusion, that it is a G-2 type spectral star, and that it is the primary energy source for the Earth. Many of us have seen a solar eclipse when the Moon blocks out the photosphere of the Sun and lets us see its corona. We know that the Sun is not just a ball of fire but a complex globe. Here are some more interesting Sun facts that are relatively new to us:

The light that we see coming from the Sun is from its photosphere. The photosphere is a thin incandescent layer that is just 200 miles (322 km) thick. That is less than one four-thousandth of the Sun’s diameter and is like the outer skin of an onion, only thinner than that.

The energy of the Sun is created in its core, which is a very small sphere, just one two-hundredth of the Sun’s volume. Every second that small ball emits the energy of 96 billion 1-megaton hydrogen bombs. The Sun’s weight decreases by 4 million tons every second as mass is turned into energy and radiated from the photosphere.

The Sun spins on its axis once a month, just as the Moon does. The center 70% of the Sun spins uniformly like a solid ball. The remaining 30% has different spins with the poles turning more slowly than the equator. These zones spinning at different speeds meet in a recently discovered zone 130,000 miles (209,000 km) below the surface. That zone is called the tachocline, and it’s where the Sun’s magnetic field originates.

Sunspots are areas where the local magnetic field is 5,000 times stronger than on the rest of the surface. The stronger magnetic field constricts the Sun’s plasma. When sunspots are rare, it seems that Earth’s climate becomes colder. Starting in 1645 there were few sunspots for 70 years. During that time, Earth became colder, people abandoned fishing colonies in Iceland and Greenland, and the Thames River and Venice canals went through periods of freezing solid.

As scientists probe more in-depth, they learn many interesting Sun facts. Just as in many other areas, the more we learn, the more questions we have. What effect do sunspots have on life on Earth? How can they affect our climate? What will happen in the next sunspot cycle? Tomorrow, we will look more into questions about sunspots. As we learn more interesting Sun facts, we realize the amazing design wisdom of the Creator to make life on this planet possible.
— John N. Clayton © 2019

Data from Astronomy magazine, July 2019, page 20.