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Spaceship Earth, Meet the Neighbours "Mercury"

The universe is vast and wonderful. It can make us feel so small and insignificant, but it can also make us feel so special that we're here.

Heading out

As we begin to head out into the cosmos, it's important to begin looking around to see what's 'out there' and where mankind might end up.

From ancient times man has looked up, into the skies and wondered just what, or who was 'out there' watching us.

As he looked into the sky, he began to see things moving around our sun, he wasn't sure what they were, so somehow in his state of wonder he began to give these objects names, names he already associated with the divine.

Blame the Romans

It was the Romans who gave the planets the names they have today, or at least the five that they could see with the naked eye.

Looking into the sky just before the dawn, he saw an orb, or sphere, it looked pink from where he was looking, warm and inviting, he called it after the goddess he already associated with love, he called in Venus.

That same sky at night showed him an angry-looking sphere, one that looked as if it was blood red, it reminded him of the blood spilled on Battlefields, so he called that one after the god of war, its name was Mars.

But there were others he saw, much larger than those two were two more, 'the biggest must be the boss' he surmised, so that one got the name 'Jupiter' and the second biggest got the name 'Saturn' after the god of agriculture.

But the fastest planet around our sun reminded them not of a 'god' but of their messenger Mercury, and that was named after him!

The nearest planet to our sun. one of five that can be seen from Earth.

The nearest planet to our sun. one of five that can be seen from Earth.

Mercury, "Messenger of the gods"

Back in ancient times, it was thought that the sun, moon and stars all revolved around the Earth, this wasn't at first a Christian idea but came from the likes of Plato and Aristotle that the early church took on board.

It made sense really, if the Earth was flat, as they thought it was back then (despite the ancient Egyptians working out that the Earth was actually round, and even working out the approximate size of the Earth as far back as 400 BCE!) then it made sense that they were all moving around the Earth, and one of them was 'scampering around' the sun moving faster than all the rest, so he must be the messenger of the gods.

For most of human history, only five planets were known about, besides the one that we live on, and our five nearest neighbours, and it's to these five that our first explorers are likely to go when we start to explore the heavens by sending people.

Actually two we certainly won't go to, one we will and two others we're probably going to go to the moons surrounding them, but going to the planets themselves, no thanks, we're not going there!

Our system, a very special place


The Earth is 93 million miles from the sun, but inside that orbit lie two other planets. Venus is actually closer to us than Mars is, but very different to Earth, closer still to the sun is Mercury.

Mercury lies about 30 million miles from the sun and is much smaller than the Earth but don't let its lack of size fool you, the composition of the planet is much denser than all of the other planets. Except for one that is, EARTH is the densest!

Astronomers use the distance of the Earth from the sun as a unit of measurement to indicate how far things are from our sun, they call the 93 million miles one Astronomical unit or AU for short.

Mercury is 0.38 of an AU from the sun and at that short of a distance for a long time it was thought to be so bound by the sun's gravity that it was 'Tidal locked' with the same side always facing the sun.

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In 1965 it was discovered that Mercury wasn't actually tidally locked, but its day is actually twice as long as it's year!

It takes Mercury 88 Earth days to orbit the sun, but 176 Earth days for it to rotate a full 'day' making it the longest day in the solar system, and during that time the temperature will rise from -173 degrees centigrade to around 400 degrees centigrade, but it isn't the hottest planet in our solar system, that honour belongs to Venus!

Battered by the sun

Being so close to the sun Mercury bears the full brunt of the solar storms that erupt every so often, anything living on the surface of Mercury would have little or no warning of solar flares erupting, these are massive plumes of plasma that streak out into the solar system and even at our distance from the sun have been known to knock out communication satellites.

Back in 1859, just as we were learning how to build telecommunication systems (the telegraph) a solar flare erupted that destroyed all electronic communication in half of the Eastern United States and Canada, these flares erupt every eleven years, and while we insulate against the normal ones, we can't plan for the bigger ones, they still destroy communication systems.

Mercury is right in the 'firing line' for these, we have sent probes close to Mercury, but they stay in orbit as landing on the surface with that kind of heat around would cause them to malfunction (keeping them in orbit we can swing them around the planet allowing them to cool off).

How big is it?

With a diameter of just under three thousand miles the planet is about one third the size of Earth, but with the difference that Mercury has no moon to help protect it, though recently Ice was actually discovered.

Yep, that's right, the planet with a daytime temperature of 400 degrees Celcius actually has places where the ice never melts!

Located at the North pole of the planet are some deep craters where one space probe showed permanently dark regions, these dark areas were realised to be always in the shade even when in the daylight, scientists did a few more tests and realised that even in the scorching heat of the 'daytime' there was ice in these areas, and not just a little but maybe as much as a few hundred billion tons of the stuff, not only that, but there is also organic material there, we just don't know what!

Ice on Mercury

And that's all for tonight folks

Here are just a few interesting facts about the nearest planet to our sun, I hope you enjoyed them

Till next time then



Lawrence Hebb (author) from Hamilton, New Zealand on July 12, 2020:

MG Singh

Its amazing some of the things we find in the scriptures of different cultures. It should make us realise just how smart ancient man was!

As for finding another Earth like planet, or one with life on it, science is looking right now.

Our present technology can give us clues about the possibility, but as yet we can't 'detect' them.

We have found over two thousand 'exoplanets' (planets orbiting stars outside our solar system, but as yet they've mostly been Gas giants the size of Jupiter and Saturn.

Recently we started finding 'super earths' thought to be rocky planets but five or six times the size of Earth.

The nearest one is orbiting Proxima Centuri four light years away, but at this stage we can't tell if it rotates or is tidally locked to its star.

To send a probe there with the present tech would take 70,000 years, but Stephen Hawking proposed a way we could do it with a tiny probe in twenty years, and we are very close to that technology!

Lawrence Hebb (author) from Hamilton, New Zealand on July 12, 2020:


Yes it is, but apparently it was Edwin Hubble studying 'redshift' in stars who figured out it wasn't the nebula everyone thought, it was too far away at two million light years, hence it must be another Galaxy!

It was Hubble who figured out that most of the other Galaxies are moving away from us, and the further away they are the faster they're moving!

Andromeda is the odd one out as it's moving towards us, but don't worry, we will be long gone when it gets here in five billion years time.

MG Singh emge from Singapore on July 12, 2020:

WE are still on the fringe of exploring the cosmos. Hindu scriptures relate of different worlds, I wonder if somewhere in the vast universe another earth with inhabitants exist. It would be wonderful if we could discover it.

Robert Sacchi on July 12, 2020:

That is interesting. Especially since Andromeda can be seen by the naked eye.

Lawrence Hebb (author) from Hamilton, New Zealand on July 12, 2020:


Very true, and it was only twenty years before Sputnik we realized there are other galaxies outside our own!

What wonders will we find?

Robert Sacchi on July 12, 2020:

It is amazing we went from Sputnik to interstellar space in less than a person's average lifespan.

Lawrence Hebb (author) from Hamilton, New Zealand on July 11, 2020:


It is, and its still doing it! I read the other day that Voyager 1 and 2 (which are still transmitting) have found things in interstellar space that have stunned science!

But more of that later



Robert Sacchi on July 11, 2020:

Thank you very much. It is amazing how exploration has completely rewritten the Astronomy books inside 1/2 a century.

Lawrence Hebb (author) from Hamilton, New Zealand on September 03, 2019:


It was those radio waves told us about the ice on Mercury. You should look up my hub 'Gazing at infinity' about Jodrell Bank radio telescope.

Lawrence Hebb (author) from Hamilton, New Zealand on September 03, 2019:


I'm so with you on that one. There are nights when i get home, its already dark and i just have to look up at the stars.

I don't know all the constellations, but those I do know welcome me home, they're so amazing.

Nell Rose from England on September 02, 2019:

I have always wanted to look up at the stars and planets without light pollution. It's not happened yet sadly. Interesting stuff! I recently wrote the music of the planets, real music translated by the radio waves that come off each planet. Mercury was very brash and scratchy!

Bill Holland from Olympia, WA on September 02, 2019:

I was out in the country this past weekend, no ambient city light, and the stars exploded from the very cool. Love these articles!

Lawrence Hebb (author) from Hamilton, New Zealand on September 02, 2019:


Just a few of the strange things we're going to encounter on this journey.

John Hansen from Gondwana Land on September 02, 2019:

This was great Lawrence. It's interesting to read that Mercury's day is twice as long as it's year, and that there is ice there.

Lawrence Hebb (author) from Hamilton, New Zealand on September 02, 2019:


That's the plan, but I'm also going to include some other 'celestial bodies' people might find interesting (like an asteroid scientists say is twice the size of the Tower of London and they think has so much gold it could make everyone on Earth into billionaires!)

So yes, and we hopefully will have fun.

Zulma Burgos-Dudgeon from United Kingdom on September 02, 2019:

Good hub, Lawrence. Astronomy is not really my thing, but I enjoyed reading this. Will you be doing a series on the planets? I hope so. This held my attention much better than my science teachers ever did.

Lawrence Hebb (author) from Hamilton, New Zealand on September 01, 2019:


My pleasure. There's some more to tell about Mercury so there might be another hub before we move on.

Lawrence Hebb (author) from Hamilton, New Zealand on September 01, 2019:


Glad you enjoyed it, and yes, we will be stopping by Pluto on the way through, we'll also be stopping by a few other places people have probably never heard of, but are special in their own way.

This hub was a bit 'rushed' so we'll probably be back next week and look at a few more strange facts about Mercury.

William Kovacic from Pleasant Gap, PA on September 01, 2019:

It's all so fascinating, Lawrence. I love studying outer space. Thanks for supplying my textbook.

Linda Lum from Washington State, USA on September 01, 2019:

So now you've given us a taste of what we have to look forward to. Good job Lawrence. Will you be including Pluto? I've always felt sorry for the poor little guy who did nothing to merit a demotion.

Lawrence Hebb (author) from Hamilton, New Zealand on September 01, 2019:


Its amazing, you can have 'cool as ice' alongside the heat of our sun!

Thought it would appeal to you.


Eric Dierker from Spring Valley, CA. U.S.A. on September 01, 2019:

Thanks buddy this is coo. - Oops, not cool like the ice ;-)

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