Tag Archives: solar

History of the Solar System by Minute Physics

I’ve only recently discovered Minute Physics, a production of Embry-Riddle Aeronautical University. They state, quite correctly in my mind, that if you can’t explain it in a minute, you don’t understand it. This echoes a statement by Bob Doms, of the University of Pennsylvania, who once said to our class, “You need to always be able to explain your work in one sentence so your mother can understand.”

This is close enough, from Minute Physics, ‘Why is the Solar System Flat?”:

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Posted by on January 10, 2014 in Uncategorized


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ImageLast week’s Science magazine had a pair of articles about Voyager 1’s arrival at the heliopause and the fluctuations of particles it has encountered. For about a year astronomers have been talking about the limits of the solar system.  An idea that I admit I had never entertained in any absolute way. Instead, my image of the extent of the solar system is mostly shaped by the most distant planets’ orbital paths. Sometime in the past decade or two, I became aware of plutoid objects, among which Pluto is one and that there is an Oort Cloud beyond that. I’ve always been a bit hazy about the details of what comprises the Oort cloud and how this differs from the plutoid objects.

Sometime during the conversation ignited by Pluto’s demotion to a dwarf planet, I head a good description of the solar system that described it as: four small, rocky planets close to the sun, then a belt of asteroids, followed by four large, gas planets, then another ring of small objects.


The edge of the solar system

I really am looking for someone to explain this in terms that a reasonably intelligent person without much astronomy background can comprehend. That is, I don’t want too much left out, but I’m not necessarily ready for an overly technical explanation.

With respect to local suns, what is the position of our solar system? What forces interact between the suns? What do we know of the space between solar systems (or between galaxies?)


A simplistic view of nine balls circling a star

That’s a pretty tidy description, but I think it leaves out a lot.

The interest now is in defining the edges, the limitation of the sun’s influence on space in favor of extra-solar forces. From what I gather, this is referring to both ‘solar wind’ and magnetic field.

I can understand this from the inside (although I need correcting here too) ,  but what I don’t fully grasp are what the forces are outside of the solar system. What dominates those forces? One thing I notice in the illustrations I’ve seen is a teardrop shape to the system resulting from a unidirectional current. What is this current? Is it emanating from other solar systems? Some local influence of nearby stars? Or a galactic force?


Heliosphere warping under external pressure

I hope someone out there can help me understand this better.

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Posted by on July 20, 2013 in Uncategorized


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Intro Biology – Photosynthesis


A note on the order of my lectures:

So far we have discussed the cell itself and divided its several functions amongst organelles that carry them out. We have also discussed the properties of membranes and how diffusion operates across them as a passive event. As a consequence diffusion can be opposed, but requires energy input. Lastly, we covered energy and how it may be converted into various forms or used to do work. Within the cell this work is often guided by enzymes.


Where we are going:

In the next section we will address how energy is captured by living things from the environment and converted into a form that may be stored. In the chapter after that, we will consider how this captured energy can be brought out of storage and converted into a useful form for enzymes to use in getting specific jobs done.




As stated above, the purpose of photosynthesis is to convert energy from the environment (solar energy) into a new chemical form (glucose) that can be stored for later use by cells.  The process of photosynthesis is completed, in eukaryotic cells, entirely within organelles called chloroplasts. These are organelles that are theoretically descended from prokaryotic cells that engaged in symbiotic relationships with larger cells but are now inseparable parts of the larger cells. As such, we recognize that there are other cells that can carry out photosynthesis, but we will restrict our discussion to that carried out in plant cells.


The basic reaction occurs in two phases, the light reactions and the dark reactions. Despite their names, both occur at the same time, typically when it is light.


The light reactions are when photons from the sun transmit energy into pigment molecules in the chloroplast. From there, electrons carry the energy from one  molecule to the next in an electron transport chain that functions to pump protons (H+) across the membrane. In this way an electrochemical-, or proton-, gradient is established.  This gradient is a form of potential energy that can be released when protons diffuse back across the membrane passively, through ATP synthase proteins that form channels through the membrane. When H+ ions pass through this channel energy is captured to synthesize ATP through a process called chemiosmosis. This is very analogous to the way that dams capture the energy of water passing through. The high energy electron is finally passed off to form NADPH, a high energy electron shuttle. Because the reaction cannot repeat until the electron is replaced in the photosystem, one is taken from H2O, which splits to form O2 and more H+ ions. The end result of the light reactions is the formation of ATP and NADPH (and O2 as a waste product) from solar energy and H2O.


This summary does not include details reactions starting from Photosystems I and II specifically. Nor does it include the cyclic reaction.


The dark reactions will be covered in our next class a little more extensively, but basically, their function is to use the ATP and NADPH produced in the light reactions as power to synthesize glucose from CO2.




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Posted by on September 26, 2012 in Uncategorized


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