The heavens declare the glory of God;
the skies proclaim the work of his hands.
— Psalm 19:1
The Earth is 7927 miles in diameter.
The Moon is 2163 miles in diameter, and averages 238,857 miles away from the Earth. This is the equivalent of 1.3 light seconds away. Light travels 186,300 miles per second.
The Sun is 864,000 miles in diameter, more than large enough for the Earth-Moon system to slip inside with room to spare. The Earth is an average of 93 million miles away. This is the equivalent of 8.3 light minutes away — the distance light can travel in 8.3 minutes.
Pluto, the furthest planet from the sun, averages 3.67 billion miles from the Sun. This is the equivalent of 5.5 light hours away.
More than 99 percent of the mass of the solar system is in the Sun, whose mass is 4.385 times 10 to the 30th pounds (4,385,000,000,000,000,000,000,000,000,000,000). This is 333,000 times the mass of the Earth.
The Sun is made of mostly hydrogen gas which is heated by continuous nuclear fusion at the core, where the temperatures are near 27 million degrees Fahrenheit. The visible surface of the Sun has an average temperature of 9950 degrees Fahrenheit and continuously radiates power of 3.85 times 10 to the 26th watts (38,500,000,000,000,000,000,000,000,000) into space. The Earth intercepts less than half of one-billionth of that power.
The Sun is a fairly typical star; most stars range from one tenth to ten times the size of our Sun. Antares, the reddish star in the constellation of Scorpius is five hundred times the size of our Sun. Our Sun and all the planets to the orbit of Mars could easily fit inside it. Antares is 400 light years from Earth.
A light year is the distance that light can travel in one year — about 5.88 trillion miles.
Alpha Centauri is the nearest star to Earth. It is 4.3 light years away — 25,000,000,000,000 miles away. The fastest men have ever traveled in space was 25,000 miles per hour (escaping Earth’s gravity on their way to the moon — which took them three days to reach). It would take 115,340 years to travel to Alpha Centauri at that speed.
Let’s look at these distances another way. Suppose you could drive your car to the Sun, 93 million miles away. At sixty miles an hour it would take you almost one hundred seventy-seven years to get there. Now imagine how long it would take you to get to Alpha Centauri in your car.
In their book, The Planetary System by Morrison and Owen, they write (pages 24-25):
To gain an appreciation of the size of the solar system and the distances between the various planets, we can make use of a scale model. Let’s reduce every dimension in the solar system by a factor of 200 million. On this scale, the Earth is the size of an orange, and our Moon would be a grape, orbiting the orange at a distance of six feet. The Sun would be a little less than half a mile away, and it would have a diameter of twenty-three feet, the height of a two-story building. It is the great distance of the Sun from the Earth that makes it appear to be about the same size as the Moon when we see both of them in our skies.
Although the Earth and the other inner planets in this model are only the size of pieces of fruit, we do have some bigger planets. At this scale, Jupiter would be a large pumpkin, still small compared to the Sun but eleven times larger than Earth. Considering the Saturn system, we find that if we measure it from one edge of the rings to the other, the planet and its rings would just fit between the Earth and the Moon. Saturn’s own large satellites would lie far beyond the moon. Obviously scales in the outer solar system are considerably grander than those we find for the planets closer to the sun.
Moving further out, we pass Uranus and Neptune before encountering Pluto, another grape like our Moon at an average distance of 18.5 miles from the twenty-three foot Sun. This is still not the edge of the solar system, however. That lies at a point where the gravitational field of the Sun is changed by the fields of passing stars. Here is where the great spherical cloud of comets lies, at a distance of some 20,000 miles from our scale model Sun. This means that our scale model solar system is about four times the size of the real Earth.
This exercise illustrates how large the Sun is, how much space exists between the planets, even in the inner solar system, and to what an enormous distance the Sun’s gravitational influence extends. The latter simply emphasizes once again how huge the distances are between the stars. The nearest star, Alpha Centauri, is five times as far from the Sun as the comets; to include it, our model would have to extend to a dimension of 100,000 miles.
Our Sun is a star in the Milky Way Galaxy, a pinwheel-shaped glob of stars 100,000 light years across and 10,000 light years thick. The Sun is 30,000 light years from the center of this galaxy. It takes 230 million years for the Milky Way to revolve once on its axis. Our Milky Way Galaxy contains at least 100 billion stars (some estimates put it at 400 billion).
The nearest other galaxy (excluding the Magellanic Clouds about 150,000 light years away) is the Andromeda Nebula which is about two million light years away from Earth (the average distance between all the galaxies in the universe) and it is 200,000 light years in diameter — twice as big as the Milky Way.
The observable universe is 30 billion light years in diameter and contains approximately 100 billion galaxies (each of which then has at least 100 billion stars, often more). Yet, the observable universe (all 30 billion light years of it) is perhaps only a fraction of one percent of the size of the universe as a whole.
When I consider your heavens,
the work of your fingers,
the moon and the stars,
which you have set in place,
what is mankind that you are mindful of them,
human beings that you care for them? –Psalm 8:3-4