Green trail, golden leaf! (part 2)

in the last post I was writing about the contest I was one, so check it out if you have not already.

It was pretty cool, and I got surprised at how the kids discussed with me so many things on my presentation.

Those were the questions I mentioned last post:


  1. Name 3 astronauts
  2. What is astronomical unit and what is light year
  3. Name 3 missions (Apollo and other count as 1)
  4. Name 4 constellations that are visible in Czech Republic
  5. Highest mountain in Solar System and where it is
  6. Where do comets come from?
  7. Difference between meteorite, meteor, meteoroid and asteroid.
  8. … (and other)

These were for younger kids and there were two more though I can not remember them..

The first question was normally quite ok, though not always they got 3. Of course most said Armstrong and Gagarin and some people said Vladimír Remek who is the first Czech astronaut.

Astronomical unit is distance from Earth to Sun and light year is the distance the light travels in one year. I thought that those would be very easy but actually to my surprise the kids usually knew what light year is but not AU, though I would guess rather the opposite.

Three missions? Most said Apollo and Sputnik (really, why Sputnik?). Some said the third which was for example Curiosity.

Four constellations are Ursa Major, Ursa Minor, Leo, Orion… and so on, we did not approve parts of constellation like Big Dipper which is just part of Ursa Major.

Olympus Moons on Mars.. few kids new this.

Nobody knew both Kuiper belt and Oort cloud I think and some teams knew one, this was kind of hard I guess.

You already know the difference from one of my posts!

Questions for older kids:


  1. What is afelium and perihelium
  2. Name all Galilean moons and give a small info for one of them
  3. What is HR diagram
  4. (Lot of pictures about life time of star)
  5. Draw the orbit of typicall comet and draw both tails and name one place where they come from.
  6. What is the heaviest element that fuses in core of star.

Afelium: furthest point to Sun. Perihelium: closest point to Sun.
Most people did not know.

Only one group was able to name Europa, Callisto, Ganymede and Io.. most did not know what Galilean moons are.

I already described HR diagram in one post, I really love it though!

There was nebulae, protostar (most people did not recognize it), normal star, red giant, supernova, white dwarf, neutron star and black hole.

Comet has very elliptical orbit and it comes either from Kuiper belt or Oort cloud as I said.
It has two types of tails:

There are two types of tails.

It is iron!





Choking black holes

people usually think about black holes as objects that will put end to anything near them tearing it apart and swallowing it for ever.

Part of this is actually true but black hole may have a problem with this because of Eddington limit.

So just a few sentences about black holes, it is collapsed massive star. There is event horizon around it and it is the region from which the escape velocity is equal to speed of light, if you cross it, you are doomed.
Astronomers observe black hole choking on a Star
Around black holes accretion disk may create. Accretion disk is disk composed of any matter (usually some hydrogen or maybe pieces of comets or asteroids). It is heated through friction and it rotates in high speeds around the black hole.

There is lot of radiation created in this process. If the object around which it rotates is smaller, some infrared radiation will be emitted. While black holes or neutron stars may emit even x-rays.

This radiation is stronger the more matter is falling into the black hole. At one point there is so much radiation that the matter will be blown away from the black hole (or star or neutron star) resulting in decrease of the radiation. When it decreases the matter will fall back to the object (not all of it) and again there is tremendous amount of radiation released, then it continues.

Every time there is tremendous loss of matter. This is for example the explanation for one star named on “c” (cygnus or something) which was losing matter sometimes in great amounts which could not be solar wind but it was this choking and exceeding of Eddington limit.

Eddington limit or luminosity is the top border for luminosity of star since if it exceeds this limit it will start to choke as I described earlier. This limit varies from object to object and it also depends on the material on which it is choking. For example if it is helium instead of hydrogen, the limit is much higher since helium is heavier element.

To read further about black holes, choking and so on, check out those pages:
Choking of black hole
Formation of accretion/debris disk around black hole
Black hole choking in the year of 2009
Kurzgesagt video: first, second


1st picture


Here it goes, here it comes! Really long time (means few years) I was wondering about dimensions. It started when I was watching videos like: how to imagine higher dimensions, what are dimensions and so on. At the beginning I did not understand any of it.

As time went on I accidentally bumped into black holes and later on into wormholes (actually this post has some mistakes as for  example it is saying that time is fourth dimension.) which should  connect space through higher dimensions and make a shortcut through Universe (picture is from here).

Ok first of all lets clear out some things. This post can have some mistakes, but I hope that there wont be any.
Second, fourth dimension is not really a time. The thing is that time does not work like space dimensions. Space dimensions also known as spatial dimensions, are the dimensions in which we can move forward, backwards, horizontaly, verticaly.. like in our world. Time is not so free, it runs just one direction and it is special type of dimension called the temporal dimension.
We live in 3+1 dimensional world.

Ok so what are those normal spatial dimensions? Well I will start with the most simple dimension, 0th dimension.
On the picture you can see 0th dimension, pretty fun huh? It is point, and point has no volume by the way, this one is just enlarged. In 0th dimension you can not do anything, I am serious.

The problem is that if you lived in 0th dimension you would not be able to imagine 1th dimension because it would be like imagining new color which you never saw.
When it comes to creating higher dimensions ALWAYS you have to copy the lower dimension infinite amount of times. This means that if you want to have 1st dimension which is line you have to line up infinite amount of points from 0th dimension. As you probably know from math there is infinite possible places to place point on line.

So here comes the 1st dimension which is line made up of infinite amount of dots. On line you can place all of the real numbers.
In the movie Flatland, which is fun movie you watch the line creatures to move back and forth because they live in 1st dimension.

I dont need to put any picture of second dimension, since you see it every day, on your computer, book on board in school.
To create 2nd dimension, again you need infinite amount of lines next to each other to create plane. Now 2nd dimension is pretty useful, for lot of stuff from: graphs, photos, any text, movies… you know I could continue for long time.
So the standard object of 3rd dimension is cube. Again when you want to create it you need infinite amount of planes because they dont have any thickness.
Well now we are in our world but of course I can continue for the fourth dimension.

Ok the problem is with imagining 4th and higher dimensions on their dimension. By this I mean that I can easily draw on plane any dimension but it is just impossible to imagine 4th dimension since in our world we dont have space to expand it into. Over time I found some things that can help you anyway.

In one episode of Futurama Doctor says: if you looked from fourth dimension to third you would see inside of this egg as when you look from third dimension to second and you can see egg’s inside. I would say that this is little mind bending. In fourth dimension there is direction in which you can move but from here we can not imagine the direction since it seems that we can already move anywhere.
Finally here comes the drawing of dimensions: Always the angle between new dimensions is 90 degrees. In

third already you have to imagine it because if you would measure the angle on the plane you would have about 60 degrees. But it continues and the angle is still 90 even if it seems impossible. 5th dimensions is just expansion of all of those dots to another direction and so on and so on (the picture is from here).

Actually from plane you can see 3rd dimension with pretty neat trick that I found some time ago. On the next picture there is 3D object in 3D, 2D and 1D. To see the first one in 3D you have to look as you would look behind it so there are fourth of those objects on row. At one point those objects would be only three because two would be over each other. If you are precise enough you can match them well enough to see the picture in 3D.
Well this is about it. (The last picture is from here.)
If you want to read about more time dimensions, check this page.
The person there assumes that with 2 time dimensions you would be able to turn around in time as you can turn around here.


Space NEWS #2

Today I am bringing space news. Just a short ones. So in last post I mentioned gamma-ray bursts. I found out that NASA found one GRB
 graph shows Fermi Large Area Telescope data from August 2008 to July 2015 for gamma rays with energies above 100 million electrhappening over and over again. As you can see on the picture there is real repeating of many and many GRBs.
Those come from black hole, a supermassive black hole from active galaxy 5,000,000,000 light years away.
It has accretion disk but scientists are not sure yet why it is in such a periods so one of many hypothesis is that there is actually second black hole which as its orbits the first one makes changes to the disk which then make some bursts bigger than other.