Showing posts with label magnetic poles. Show all posts
Showing posts with label magnetic poles. Show all posts

August 3 - First Watercraft to Reach North Pole

    Posted on August 3, 2022     


This is an update of my post published on August 3, 2011:




The USS Nautilus was the world's first operational nuclear-powered submarine. Because of her nuclear propulsion, she was able to remain submerged much longer than diesel-electric submarines, and so she was able to break many records and establish many firsts. One of her most famous exploits was achieved on this day in 1958, as the submarine reached the geographical North Pole.

The submarine began this West Coast voyage, called Operation Sunshine, in April of that year, and she tried to enter the Arctic Ocean in mid-June. However, there was deep draft ice that made it too dangerous. The Nautilus went all the way to Pearl Harbor in Hawaii to wait for better ice conditions. In late July, it was deemed safe to try again, so the Nautilus traveled north again and submerged in the Barrow Sea Valley on August 1. The submarine reached the North Pole on August 3 and continued on another 96 hours (4 days) until she could surface northeast of Greenland.





This is the USS Providence celebrating
the 50th anniversary of the Nautilus's
polar crossing--in the Arctic Ocean, of
course!


What is the geographical North Pole?

It is the point in the northern half of Earth where the planet's axis of rotation meets its surface.

On a globe, it is the spot where the upper portion of the metal rod around which the globe spins emerges from the Earth's sphere and attaches to the globe's stand.


The South Pole, of course, is the point in the southern half of Earth where the axis of rotation meets the surface. And on a globe it is the spot where the lower portion of the rod emerges.


Did you know...?

  • The North Pole is defined as the northernmost point on Earth. It lies exactly opposite the South Pole, which is the southernmost point on Earth.
  • The North Pole lies in the middle of the Arctic Ocean, although that ocean is sometimes covered in ice, and the South Pole is in the middle of the ice-covered land mass that is Antarctica.
  • Earth has a slight wobble in its spin. For this reason, the North Pole isn't in one fixed location—but instead it ranges around a few meters.
  • The Magnetic North Pole is the point on Earth's Northern Hemisphere at which Earth's magnetic field points downwards. It is not the same spot as the Geographic North Pole, and it slowly changes over time. The Magnetic North Pole was in Canada in 2001, and it has been moving toward Russia more than 30 miles (more than 55 kilometers) per year! (Learn more here.)







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January 16 – Discovering One Out of Two South Poles

Posted on January 16, 2019

Two South Poles?

Huh??

To understand what we mean by "two South Poles," let's think clearly what we mean by "pole."

You probably know that the Earth and other planets are mostly spherical balls that are captured by the Sun's gravity, so that they revolve around the Sun - but they are also spinning, or rotating, on their own axes. 

As you can see from this chart, the various planets don't have
identical tilts on their axes, and they don't even all spin the same
direction.


In some ways, therefore, they are like a globe that can only spin on the axis running between mounts above and below the globe. 




Some (not all) of the planets have magnetic fields. The Earth's magnetic field seems to be caused by the motion of the molten rock in the outer core; the field curves outward near the South Pole, turns "up" toward the equator and the Northern Hemisphere, and then turns down again near the North Pole, re-entering the Earth there.



Notice that I said "near" the poles. The magnetic poles are not exactly the same as the geographic poles, and the magnetic poles are always on the move. Currently, scientists tracking the magnetic field and its poles are puzzled about why the north magnetic pole is suddenly moving more quickly. Check out this breaking news here.

From 1908 until 1909, English explorer Ernest Shackleton led a small expedition that set a record for the southernmost point ever reached. During that "Great Southern Journey" Shackleton and his companions also became the first to climb Mount Erebus, the most active Antarctic volcano, and they also were the first people to reach (on this date in 1909) the Magnetic South Pole.




On a later expedition, Shackleton's ship was trapped
in pack ice and was slowly crushed. The crew escaped,
but the men had to make their way back to civilization
on small lifeboats on a stormy ocean.

So Antarctic exploration was dangerous even for
experienced explorers!

Actually, although Shackleton and company returned to England from the "Great Southern Journey" as heroes, they had failed to reach one of their goals. They had hoped to reach the geographic South Pole, which was even farther and more difficult than the magnetic pole - and the geographic pole was the one everyone seemed to care about. 

Even though they didn't reach that goal, it turned out that Shackleton had turned back at the right time. The men were on half-rations on the trip back to the spot where they would catch their return ship, and they barely made it back in time to catch that ship! On the trek back, one of the explorers (Frank Wild) was doing so poorly that Shackleton gave Wild the only biscuit he, Shackleton, was allotted for the day, so that Wild would have two. Wild wrote in his diary, "All the money ever minted would not have bought that biscuit and the remembrance of that sacrifice will never leave me."

When Shackleton was safe back in England, he seemed not to regret making the decision to turn back when they did. He said only one thing to his wife about not reaching the geographic South Pole, "A live donkey is better than a dead lion, isn't it?"

Of course she agreed!

In 1911, Roald Amundsen won the "race" to the geographic South Pole.








Other planets' magnetic fields:

Since Venus, Mars, and our Moon do not have magnetic fields, we think that their cores are cold and inactive. 

Mercury only has a very, very slight magnetic field. From Mercury's size, scientists had assumed its core would be cold and inactive, but maybe the Sun being so nearby keeps the core a bit active?

Saturn's magnetic field is completely lined up with its geographical axis (the only planet in which this is the case). Jupiter has a magnetic field that is more normal, with its magnetic poles close but not exactly the same as its geographical poles. Scientists think that their magnetic fields are caused by layers of liquid metallic hydrogen rubbing against one another.



Uranus is entirely unique in its axial tilt. At some point in the history of the solar system, we think, another largish body must have slammed into it, leaving it to spin on an axis that is just about "flat" - in other words, its axis is pretty much on the same plane on which it moves around the Sun. So it seems to be spinning "lying down." It's been called "the tipped-over planet."

But Uranus's magnetic field has a more normal orientation than its rotational axis, which means that its Magnetic North Pole is about 60 degrees away from its Geographical North Pole (and of course the same with the South). 



Neptune's magnetic field, like Uranus's, is way off-kilter from its axial tilt. In both of these planets, the magnetic field does not go through the center of the planet, but rather tips off to one side. Scientists think that the fields are caused by layers of water.





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December 11, 2011 - First Recorded Sighting of the Aurora Borealis in America




– 1719


The Aurora Borealis is another name for the Northern Lights—the dancing “curtains” of light that sometimes appear in the night sky in the far north. (The same thing in Antarctic regions is called the Aurora Australis.)



Of course we know that this natural phenomenon had been seen many, many times before 1719—by, for example, the many native peoples of Alaska and Canada—but for the English settlers in New England, it was a new and unexplained sight. Many witnesses in New England, on this day in 1719, saw a mysterious face looking back at them from the sky. Some responded with fright, thinking that this was a religious experience foretelling the “last judgement.”

Now we know the true explanation: the sun not only emits light, but also charged particles such as free electrons and positive ions. These energetic particles pour down on the surfaces of all the planets and moons, but because Earth has a magnetic field, the particles are redirected and then funneled downward to the north and south poles. When the particles collide with atoms in the upper atmosphere, those atoms emit light.

Auroras tend to get brighter whenever there are sunspots on the sun, because these dark spots indicate solar magnetic storms that cause the sun to emit more charged particles than usual.

By the way, Earth acts like a giant magnet because of the rotation of its molten core. Venus, which is the closest planet to the Earth and also its twin in size, does not have magnetic fields. Scientist think that Venus must have a iron core similar to Earth's, but the planet's very slow rotation—one Venus day is 243 Earth days!—is just too slow to produce the dynamo effect that causes Earth's magnetic fields.

Can you find out which other planets do or do not have magnetic fields? (Hint: most of them do.)


Also on this Date:


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