Magnetic Fields: Its Purpose on Earth

Hi everybody,

If you have used a compass, then you have used one of Earth’s key features to find your way. That feature is Earth’s magnetic field.

Earth is a giant magnet. This is because the core generates the magnetic field using the process called the geodynamo. The geodynamo process works like this: the outer core is full of conductive metals that is heated from below by the inner core. This drives the convection. The convection in the outer core is maintained by the heat in the inner core, and chemical differentiation. With help by the rotation of the Earth, this drives convection, and creates an instability that forms the magnetic field, and this process aligns the magnetic field to the rotational axis of the planet.

The Geodynamo Process

Magnetic fields are essential for life on Earth. That is because the magnetic field protects the planet from cosmic rays and charged particles from solar flares. When the charged particles hit the magnetic field, they become trapped and slide along the field lines moving towards the poles. The strongest areas of the magnetic field are near the poles, and if the particles are not strong enough, then they are repelled and they bounce back and forth along the field lines and that creates the Van Allen Radiation Belts. There, the magnetic field has trapped the charged particles to prevent them from reaching the atmosphere. If we didn’t have the magnetic field protecting the Earth, then the atmosphere would become stripped of its atoms and the radiation from the solar wind would irradiate all life on Earth.

Van Allen Radiation Belts

However, the charged particles also interact with the magnetic fields. The motions of charged particles in circles form magnetic fields of their own. As a result, when both magnetic fields collide with each other, Earth’s magnetic field absorbs the momentum of the charged particles, and that pushes Earth’s magnetic field back. The Earth wants to make an even magnetic field, but the Sun is pushing the magnetic fields away from the sun. It’s not an even bombardment, due to the variations in solar output.

There are times when the solar wind is strong enough to overcome the magnetic field. The charged particle slides along the field into the poles, and when it is strong enough, it enters the atmosphere near the Earth’s poles, and ionizes the atmosphere. This leads to a beautiful sight called the Aurora Borealis/Australis.

Auroras over the landscape

Earth is not the only planet with a magnetic field though.

Stay tuned for my next post.



Coursera Lecture – Week 5.8






The Search for M51

Friday, March 14, 2014 was clear despite a weather forecast of overcast skies. With that in mind, I decided to take my telescope out to observe the night sky and confirm what I saw last session was M51.

At midnight, I took all my equipment outside and I set my telescope up for observation. However, when I turned the mount on, it gave me errors 16 and 17. Both altitude and azimuth motors were unresponsive. I realized that the software thinks the mount is the GPS model instead of the SE model. This caused a conflict which caused me to take everything back inside. Once all my equipment was safe, I brought my mount to the computer to update the software. After updating the software to the correct model, I brought everything back outside and continued setting up.

Earlier that day, I was able to move the finderscope from its current position and screwed it in the same location of the piggy back mount. However, when I was calibrating the finderscope, the knob wouldn’t turn all the way to the target body (the Moon). Therefore, I decided to get the telrad (a superior finderscope) and tape it onto the telescope. I then calibrated it to the Moon.

When my telescope was pointed on the Moon, I realized that my neighbour’s house was starting to obstruct the Moon. At the same time, I realized that Mars was clearly visible from my position. I decided to slew to Mars’ position and I saw a beautiful red dot. However, I could not make out any detail. It’s still moving towards opposition, therefore it will get bigger, and hopefully clearer.

I decided to switch my eyepiece from 25 mm to 20 mm to get more magnification and get closer to the planet. After switching the eyepieces, it was out of position. However, I was able to find Mars again. It was slightly bigger in this lens than in the previous lens. It was great to get closer to the planet. After staring at the beauty of Mars for some time, I decided to search for M51.

I moved my telescope to an area where the stars near zenith were not obstructed by trees. I scanned at the same part of the sky where I first saw it, but I didn’t find anything. I found its RA/Dec Coordinates, and slewed my telescope to the coordinates using its computer, but the telescope slewed to the wrong area. I tried slewing to its approximate alt/az coordinates using the SkyView App on my iPhone, and slewing to those coordinates using the computer. However, that didn’t work out either. I was becoming frustrated. Eventually, the clouds moved in, and I had to pack up.

I solved a lot of issues this session, such as my mount, and my finderscope. In addition, I also found Mars. It was an incredible sight. The last time I saw Mars was at 5 am in the park. I hope to see it again, preferably at opposition, when it will look big. Sadly, I could not find M51. However, in retrospect, I realized that moving the teIescope caused my failure to find M51, because the telescope didn’t know that it moved from its current position. That is the reason why my telescope failed to find M51. I hope to prevent that in the future.

Clear Skies to you all!

Return of the Observer

Hi Everybody,

These past months have been somewhat difficult. My telescope was experiencing technical difficulties. However, I was able to resolve the issues, and I can continue observing now. Here is my recollection of my latest observations:

During the night of Saturday March 8, 2014 the skies were clear. Before that, an old Newtonian was discovered in my family’s closet. It’s a cheap one with only 30x magnification, but works nonetheless. That night, I looked at the moon with it. It definitely projects an image, but not a clear image. It looked very dusty. The image is not as good as my 8″ SCT (Schmidt-Cassegrain Telescope). After observing the moon, I decided to take my SCT outside the driveway to find Jupiter.

Because of my issues with my telescope, I had to recalibrate my finderscope with my Telescope. Luckily, the Moon was above the horizon. I was able to find the moon after some struggle, and calibrate my equipment with it. It was satisfying to see the moon up close since my telescope developed problems. Pointing away from the light side of the moon I saw, without light interference, how the dark side of moon and the darkness of the sky look compared to each other. It was intriguing.

Sketch of the Moon meshing with space.

Sketch of the Moon meshing with space.

After that, I decided to find and look at Jupiter. It was easy to find Jupiter, falling to the horizon on the western Sky. Looking at it through my 25 mm eyepiece, it looked the same as always. In addition, three of its four moons are visible. It was lovely. However, I had an idea. The newtonian telescope that my family found has a 20 mm eyepiece. I know that when you divide the focal length of the telescope with the focal length of the eyepiece, you get the magnification of the telescope. A 2032 mm telescope with a 25 mm eyepiece will yield 80x magnification. Knowing that, I decided to put the 20 mm eyepiece from the newtonian onto the SCT. If the math is right, then my telescope should have 101.6x magnification and, as a result, Jupiter should appear larger. I put on the eyepiece, and then my put my eye on the eyepiece, and I saw a slightly bigger Jupiter. It was beautiful. If the math continues to hold, then I plan on getting smaller eye piece to get closer to Jupiter. It was a step forward in my astronomical journey.

My next object I wanted to observer were the galaxies located at opposite sides of Benetnasch, which is part of the Big Dipper. It took a while to set up. I had to dig out an area of snow in the backyard to place my telescope. After a while, I was able to safely move my equipment to the dug out area, where I set up my equipment. I went about aligning my telescope to the limited about of stars visible. The first time failed for some reason. However, the second time was a success. I pointed my telescope towards the big dipper scanning for that object. However, I failed to find anything. During my search, I stumbled upon a star that had a clear halo around it. It was quite amazing to see such a star like that. I was thinking it was a deep sky object. However, I didn’t know. But it did look like this:

The star halo I saw was a bit more pronounced than the image.

Looking at my clock, I realized it was three in the morning. Daylight Saving Time had already come into affect, which means it was actually four in the morning. Knowing that, and that the cold is starting to get to me, I decided to pack it in for the night bringing all my equipment inside safely.

Overall, It was a successful observation. I saw the beauty of the moon, Jupiter, and an intriguing star. When I was doing research and talking to experts, I learned that it might be a deep sky object with only the heart visible, either M51 or the Ring Nebula. It’s interesting that a galaxy could look like that to my eye. However, I can’t be sure; not until I see it again and image it. I have taken many steps forward in my astronomical observations. I hope to continue that in the coming days.