The Solar System
Part I
Our solar system; also known as home sweet home.
Here is where we live. The familiar is here.
So, let's learn more about this place!
At the center of it all
The heart of, and driving engine for, the solar system is the Sun (more formally known as sol).
It is the Sun's gravity that holds everything together. It is the Sun's energy that ultimately powers just about everything that takes place in the solar system. And, lest we forget, it also adds beauty in our world.
Far from being just a big bright ball in the sky, its surface is an incredibly violent, bubbling, stormy, hot place to be. Temperatures there are in the ballpark of 10,000º F! And in terms of size, over a million Earths, or 900 Jupiter-sized planets, could fit in it.
Impressive!
Close friends
The group of four planets nearest to the Sun are, naturally, called the inner planets. Let's explore one at a time.
Mercury
First, comes Mercury.
Being so close to the Sun, Mercury must whirl around it very quickly – taking only 88 days to complete one cycle. In fact, due to its closeness to the Sun, we can occasionally see it cross or “transit” the Sun.
Living on Mercury would be very different than on Earth for many reasons. For starters, the Sun would appear to be twice as large and a lot brighter. Also, Mercury has effectively no atmosphere – we couldn't breathe. But perhaps one of the strangest differences is that Mercury spins on its axis slow enough to almost keep up with its rotation around the Sun every 88 days. Result? Standing on Mercury, the Sun would take 176 Earth days to rise and set.
Makes for a long day at the office!
Venus
The next planet out is Venus.
Since Venus is closer to the Sun than the Earth, it will be seen near the Sun. However, unlike Mercury, it is not so close that it cannot be seen separate from the Sun. For this reason, it is often called the evening and morning star – often being the first seen at sunset or the last at sunrise.
For a long time, it was believed that Venus would be a tropical paradise in the solar system. However, probes to the surface revealed the exact opposite.
Venus surface as taken by Venera 13, 1982
The facts are grim:
On a cool day, the temperature of Venus is about 900º F. (Consider how hot that would be when a household oven usually only goes up to 500º F.)
The pressure on Venus is about 90 times as high as on Earth. For comparison, this is about the same pressure as half a mile below the ocean surface.
The clouds high in the atmosphere contain sulfuric acid.
In short – not a good place for a summer home.
Earth
The Earth is the only planet in our solar system that is inhabited. Small wonder, we sit in a narrow range called the habitable or “Goldilocks” zone – too close and the Sun's heat will make life unlivable. Too far away and the Sun can't warm us up enough.
We are … just right.
Mars
Named for the Roman god of war, the red planet Mars is the last of the inner planets.
Mars does have an atmosphere but, at just 1% that of Earth, it is barely existent. Mars has two moons, Deimos and Phobos.
Deimos
Phobos
The surface of Mars itself has a few notable features:
Martian "canals" – When astronomers started getting a good look at Mars they saw features that were believed to be a vast martian canal system. This was taken to be evidence of a martian civilization of advanced engineering abilities that could construct a vast canal network to transport water around the planet.
Olympus Mons – A martian volcano, the largest known mountain in the solar system. It tops off at about 13 miles high or over twice the height of Mt. Everest.
Valles Marineris – A large system of canyons over 100 miles long and up to 4 miles deep. This is three times as deep as the grand canyon and the second-longest such valley known to be in the solar system.
To be continued …
Tune in next time to read more about the fascinating world that is ... The Solar System.
Great Books
War of the Worlds
Written in 1898 by H.G. Wells, this is the original invasion by aliens book. The story challenges our human sense of superiority over all other creatures – even on other planets.
The opening paragraph sets the stage perfectly:
No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinised and studied, perhaps almost as narrowly as a man with a microscope might scrutinise the transient creatures that swarm and multiply in a drop of water. With infinite complacency men went to and fro over this globe about their little affairs, serene in their assurance of their empire over matter. It is possible that the infusoria under the microscope do the same. No one gave a thought to the older worlds of space as sources of human danger, or thought of them only to dismiss the idea of life upon them as impossible or improbable. It is curious to recall some of the mental habits of those departed days. At most terrestrial men fancied there might be other men upon Mars, perhaps inferior to themselves and ready to welcome a missionary enterprise. Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us. And early in the twentieth century came the great disillusionment.
And so Earth gets invaded by Martians. Ironically, they fail due to the same short-shortsightedness – they succumb to Earth's disease.
The book is for older readers due to content – descriptions of death and destruction by the Martians and a brief (purely scientific) discussion of martian reproduction. Nothing overly graphic.
On the web
Mercury Transit Captured in Stunning Time-Lapse
This video shows a time-lapse movie of Mercury transiting or crossing the Sun.
How to view the Transit of Mercury
Professor Lucie Green explains what a transit is and how to safely view it.
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