Showing posts with label heliocentric. Show all posts
Showing posts with label heliocentric. Show all posts

February 19 - Happy Birthday, Nicolaus Copernicus

Posted on February 19, 2021

This is an update of my post first published on February 19, 2010:




The Germ
an/Polish polymath (a person who is learned in many different fields) Nicolaus Copernicus was born on this day in 1473. He was an astronomer, mathematician, doctor, translator, artist, Catholic clergy, jurist (one who studies, develops or applies the law), governor, military leader, diplomat, and economist. He was a polyglot (a person who speaks many different languages) as well; he spoke German, Latin, and Polish with equal fluency, and he also knew Greek and Italian!

During his lifetime, Copernicus
 might have been known to many as his powerful uncle's personal secretary, perhaps, or as the published translator of some poems written in Greek. However, we know him today from his contributions to astronomy and, more generally, to science.



Even though astronomy was just a sideline for Copernicus, he was able to work out the heliocentric, or sun-centered, model of the solar system.

For thousands of years it was thought that the Earth sat still at the center of the universe, and everything people could see in the sky, from the Moon and Sun to the planets and stars, circled around it. People thought this was true because we experience the world this way—as we stand on the Earth, we do not feel as if it is in motion, and we clearly see the Moon, stars, and Sun moving in our skies.

However, in order for our observations of the observed movements of the planets to make sense, we cannot suppose their paths around the Earth to be simple circles. Instead, thinkers like Ptolemy invented little circles cycling around larger circles—epicycles, deferents, and equants—in a very complicated system.



Copernicus demonstrated that, by simply moving Earth out of the central spot and supposing that it was in motion, too, most of those complications fell away.


Copernicus's system started with the idea that the Sun is the unmoving center of the universe. Mercury and Venus circle the Sun in closer orbits than the Earth's, and Mars, Jupiter and Saturn circle the Sun in farther orbits. According to Copernicus's model, the firmament doesn't move; this outermost celestial sphere was pictured as a sort of rigid shell onto which the unchanging stars were attached.

The fact that the unmoving sun and firmament (the stars) seem to move around the Earth once per day was explained, in the new Copernican system, by the idea that the Earth itself is spinning around like a top, rotating on its axis once a day. So the Earth has two motions—spinning on its axis and revol
ving around the sun.


You probably noticed...

...Hopefully you noticed that Copernicus wasn't entirely correct in every aspect of his heliocentric model of the universe.* However, he was correct that the sun was the center of the solar system, and this Big Idea was so important to astronomy, science and philosophy, that scientists have credited him with starting a scientific revolution!
*The sun is not actually the center of the universe. It's pretty far out from the center of the Milky Way galaxy, even, hanging out in an obscure corner of one of the spiral arms. Nor is the Milky Way galaxy the center of the universe. As a matter of fact, the phrase “the center of the universe” might not even make sense.

 



Also, there is no firmament. There is no solid
 shell or sphere onto which stars are glued. Instead, the stars are much larger and much farther away than they seem, great balls of burning gas similar to our sun, and they are at all different distances away from us. Stars—even our sun—are in motion, too, revolving around the center of their galaxies even as the galaxies rush away from each other. Also, the stars certainly aren't unchanging—new ones are born, older ones die.

 

The firmament - which of course doesn't actually exist - is pictured here in gold.

 

Finally, of course, there are many bodies in the solar system that Copernicus didn't know about, most noticeably two more planets, Uranus and Neptune.

Ahead of Hi
s Time
Copernicus's
 Big Idea was a bit too radical for most people of his time, and for more than a century, most people didn't accept it. Remember, some of Galileo's findings confirmed the Copernican system, but he was put on trial and then under house arrest because of it—and that was 100 years later!

Watch a short video about Copernicus.


Find out more about Copernicus's Big Idea.

Check out how much simpler the Copernican Sun-centered system is than the Ptolemic system of old here. This website has a lot of great info - and you can scroll down to a simple animation comparing the two systems.

Copernicus has been honored with many memorials, with his face on Polish money, with a crater on the moon named for him, and most recently with a new element (atomic 
number 112) named copernicium.

This salt sculpture of Copernicus can be found
in a salt mine in Poland.






(Third Friday in February)

December 14 – Happy Birthday, Tycho Brahe

Posted on December 14, 2014


Today we celebrate one of the biggest of Europe's early astronomers: Tycho Brahe.

This drawing shows Ptolemy's
 theory of a geocentric
(Earth-centered) universe.
A long time ago some very intelligent, learned, and wise men in Ancient Greece thought long and hard about a lot of things, and they decided that the heavens – the stuff we see in the sky – was perfect and unchanging. Everything in the skies seemed to move in regular rhythms, and they shone with perfect, unblemished light, and things stayed the same year after year, century after century. The perfect, unchanging heavens became a part of the Greeks' philosophy about the universe.

Another thing that was self-evident as these learned men looked upwards: everything circled us! We Earthlings were the center of it all! The Moon and Sun clearly circled the Earth, as did the stars. The planets had more complicated motions – with a little bit of backwards action interrupting their progression across our skies – but they also basically traveled around our world.

This is a modern diagram of Ptolemy's
system. Note that the Sun and Moon
and the sphere of stars simply orbit
around the Earth...but those pesky planets
with their back-and-forward motion must
be doing cycles in their cycle, Ptolemy thought. 

But the Scientific Revolution upset all of these notions:

In the 1540s, Nicolaus Copernicus published his theory that the Earth was NOT the center of the universe. His theory was that the Earth and other planets traveled around the Sun – although he kept those perfect circular orbits thought up by the Greeks.

This was SO not cool with people – after all, we liked being the center of things!





In 1609, Johann Kepler published his theory that the Earth and other planets actually traveled around the Sun in non-perfect oval orbits.

Non-perfect orbits?!? What's the universe coming to?




The next year, Galileo Galilei published his findings from studying the universe with his newly built telescope. He had discovered four tiny lights that clearly revolved around the planet Jupiter. This was proof that Copernicus was right, at least in the idea that not EVERYTHING in the universe revolved around us! And Galileo argued that Copernicus was right about the big idea of the Earth circling the Sun, rather than vice versa, as well.


Still not cool with most people! Galileo was put under house arrest.


Sandwiched between Copernicus, on the one hand, and Kepler and Galileo, on the other, was today's birthday, Tycho Brahe. His big contribution to tearing down the Greeks' perfect heavens was proving that the heavens were not unchanging.

One of the supernovas
that Tycho observed was
one that appeared in 1572.
Brahe (who was born on this date in 1546) carefully observed a number of “new stars,” called stellae novae – now called novas and supernovas. Because of that “the heavens can't change” rule, people thought that new stars in the sky were local phenomena, found in Earth's atmosphere, or at least closer to Earth than the Moon. But Brahe knew that, if the new stars were that close, they should appear to be in slightly different spots in the sky, compared to the distant “fixed stars,” when seen from different observers positioned many miles away from one another. This parallax didn't occur, however, thus proving that the stars were, in fact, much farther away from the Earth than the Moon – that they were, in fact, part of the heavens.

And, voila, Tycho had proved that the heavens could change!

By the way, Tycho did not think that Copernicus was right about the Earth traveling around the Sun. He didn't go along with the Ancient Greek idea of everything circling the Earth, either – instead, he came up with his own system:

  • The other planets circled the Sun.
  • The Sun and the Moon circled the Earth.
  • The “fixed stars” circled everything.

You may be wondering why Tycho didn't agree with Copernicus. He had two important arguments: 

1) the Earth was too sluggish and heavy to be continuously in motion, and
2) the Earth's orbit around the Sun, if it existed, would cause stellar parallax.

(Actually, there IS stellar parallax  the Sun, planets, and nearby stars can be seen to be in slightly different positions, compared to farther away stars, when the Earth is on opposite sides of its orbit. But the angles are very small and difficult to measure. Tycho knew that the apparent lack of parallax wouldn't be a problem if there was an enormous gap between the outermost planet  which at the time was Saturn  and the stars. But such an enormous gap seemed ridiculous to Tycho and other scientists.)

About that enormous gap...


Tycho Brahe thought an enormous gap between Saturn and the rest of the farther-off universe (stars and such) was ridiculous. But that enormous gap is true!

Saturn is only hundreds of millions of miles away from Earth, but even the nearest stars are TRILLIONS of miles away!

And just one trillion is a million millions! So think about how far many trillions of miles are!

To give you just a bit more perspective on how much a trillion is, think of it this way:

Count one second. It's about as long as it takes you to say “A thousand one.”

Now consider this: The United States has not yet existed for a trillion seconds! As a matter of fact, almost nothing in your history books had happened yet, a trillion seconds ago! Not Tycho Brahe's birth, not the Ancient Greeks, not even the Ancient Egyptians!

As a matter of fact, a trillion seconds ago is about 31 THOUSAND years ago, and humans were just figuring out how to fire pottery and inventing the bow and arrow!




To learn more about Tycho Brahe, check out this earlier post.



Also on this date:


Arrival of the Yule Lads in Iceland









































Plan ahead:

Check out my Pinterest pages on:
And here are my Pinterest boards for:

February 19, 2010
















Happy Birthday, Nicolaus Copernicus





This Germ
an/Polish polymath (a person who is learned in many different fields) was born on this day in 1473. He was a mathematician, astronomer, doctor, translator, artist, Catholic clergy, jurist (one who studies, develops or applies the law), governor, military leader, diplomat and economist. He was a polyglot as well, speaking German, Latin, and Polish with equal fluency and also Greek and Italian.

During his lifetime, Copernicus
might have been known to many as his powerful uncle's personal secretary, perhaps, or as the published translator of some poems written in Greek. However, we know him today from his contributions to astronomy and, more generally, to science.

Even though astronomy was just a sideline for Copernicus, he was able to work out the heliocentric, or sun-centered, model of the solar system.

For thousands of years it was thought that the Earth sat still at the center of the universe, and everything people could see in the sky, from the Moon and Sun to the planets and stars, circled around it. People thought this was true because we experience the world this way—as we stand on the Earth, we do not feel as if it is in motion, and we clearly see the Moon, stars, and Sun moving in our skies.

However, in order for our observations of the observed movements of the planets to make sense, we cannot suppose their paths around the Earth to be simple circles. Instead, thinkers like Ptolemy invented little circles cycling around larger circles—epicycles, deferents, and equants—in a very complicated system.


Copernicus demonstrated that, by simply moving Earth out of the central spot and supposing that it was in motion, too, most of those complications fell away.

Copernicus's system started with the idea that the Sun is the unmoving center of the universe. Mercury and Venus circle the Sun in closer orbits than the Earth's, and Mars, Jupiter and Saturn circle the Sun in farther orbits. According to Copernicus's model, the firmament doesn't move; this outermost celestial sphere was pictured as a sort of rigid shell onto which the unchanging stars were attached.


The fact that the unmoving sun and firmament (the stars) seem to move around the Earth once per day was explained, in the new Copernican system, by the idea that the Earth itself is spinning around like a top, rotating on its axis once a day. So the Earth has two motions—spinning on its axis and revol
ving around the sun.

You probably noticed...

...Hopefully you noticed that Copernicus wasn't entirely correct in every aspect of his heliocentric model of the universe.* However, he was correct that the sun was the center of the solar system, and this Big Idea was so important to astronomy, science and philosophy, that scientists have credited him with starting a scientific revolution!
*The sun is not actually the center of the universe. It's pretty far out from the center of the Milky Way galaxy, even, hanging out in an obscure corner of one of the spiral arms. Nor is the Milky Way galaxy the center of the universe. As a matter of fact, the phrase “the center of the universe” might not even make sense.

Also, there is no firmament. There is no solid
shell or sphere onto which stars are glued. Instead, the stars are much larger and much farther away than they seem, great balls of burning gas similar to our sun, and they are at all different distances away from us. Stars—even our sun—are in motion, too, revolving around the center of their galaxies even as the galaxies rush away from each other. Also, the stars certainly aren't unchanging—new ones are born, older ones die.

Finally, of course, there are many bodies in the solar
system that Copernicus didn't know about, most noticeably two more planets, Uranus and Neptune.
Ahead of His Time
Copernicus's
Big Idea was a bit too radical for most people of his time, and for more than a century, most people didn't accept it. Remember, some of Galileo's findings confirmed the Copernican system, but he was put on trial and then under house arrest because of it—and that was 100 years later!

Watch a short video about Copernicus.

With the animated sequences about orbits, this one makes Copernicus's Big Idea easy to understand.


Read more about Copernicus's Big Idea.

This website explains the Sun-centered system with words and diagrams.

Copernicus has been honored
with many memorials, with his face on Polish money, with a crater on the moon named for him, and most recently with a new element (atomic
number 112) named copernicium.