Green trail, golden leaf!

this is very abstract title I guess but it summarizes why I did not post last Saturday when I planned, yes I am sorry. Anyway I was on this contest called Green trail, golden leaf which is contest of mostly biology though there is also astronomy, meteorology (not this year) and geology. I was not contestant for the first time, but organizator and I helped with astronomy site.

There are two categories which are basicly for older (10-15) and younger (0-10) kids (numbers are rough). The contest happens in groups of 6 people. They are then walking the trail three at a time, getting points on various sites on various topics and finally their points add up.

In Friday I had actually presentation first. I was pretty happy how I did it except that it was a little bit too long. The problem was that even that the presentation was for roughly 50-60 minutes the kids were discussing and asking questions a lot (which made me happy of course) but finally the presentation was roughly 100 minutes.

I was talking about the view on Earth, geocentrism, heliocentrism, no centrism at all and why the Universe is so big and why people usually think it is not. I followed up with aliens and Fermi paradox, of course wow signal and KIC xx… were also mentioned. In the end I mentioned SpaceX, terraformation of Mars, New Horizons and Voyager.

As I said the presentation was going pretty good as well as the contest itself. For younger kids we had questions like:

  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)


For older it was bit more difficult:

  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. … (and other)

From 12 sites astronomy was the 2nd toughest ūüėÄ

Lets see how would you do, I will return to it some other post.


Blogger Recognition Award #2


two months back I was nominated by Chape for this type of award and about week back it happened again! Thanks to The Nexus Science for the nomination, I was already nominated once by you and now again which is amazing! Thank you very much again.

The Rules:

  • Thank the person who nominated you and provide a link to their blog.
  • Attach the award to your post.
  • Write a brief story / history of your blog.
  • A take down of advice to new bloggers.
  • Nominate 10 other bloggers.
  • Comment on their blogs to notify them of the nomination.


I started more than an year ago which is quite long time blogging when compared to others. Throughout the time I wrote about physics and astronomy but now I also write about chemistry, optics and other interesting stuff. Mostly I stopped writing about the kind of popular science like fundamental forces since I realised that it is actually not so simple as I thought it was. Last december or so I started to write a lot and right now I keep up with one post every other day.


Just join the community, it will earn you popularity fast enough.






Flights of Fancy


Meteor, Meteorite, Meteoroid?

as the title points out I will write today about meteors, meteorites, meteoroids and asteroids. I have to say that before I searched it was not sure which one is which.

Lets start with asteroid.


These things are the largest. You probably know few of them because the biggest are also called minor planets or dwarf planets. There are quite lot of them, the biggest one inside of the orbit of Neptune is Ceres, that is the dwarf planet with these cool bright spots. There are quite few types based on what are they composed of. There are carbonate, silicate and metallic asteroids for example.

Lot of them are also in the Kuiper belt.


This one is a bit tricky. It is smaller asteroid, sometimes just a dust. The important thing is that as well as asteroid it has to be flying in outer space to be itself. Of course there are millions and millions of these objects. Usually they are considered to be smaller than one meter. When such object enters the atmosphere it can be fast as 20 km/s!


Meteor is more often known as “shooting/falling star”. It is just the event when meteoroid enters the atmosphere and heats quickly since as I said it is pretty fast. In some time of the year Earth goes through dust that was left by comets. Those are called meteor showers. When meteor shines bright enough, more than any planet in the night sky, it is considered fireball, which was for example Chelyabinsk meteor.


Meteorite is object that survives the path through atmosphere and impacts Earth (or other object, Mars or Moon for example). Of course quite often these things shatter a lot. People are than trying to find the debris. Also some are quite dangerous and can easily kill person even if they are very small. The largest one piece has stunning 60 tonnes.


Impact on roof 

What is going up on Mars?

while thinking about today’s topic I find some random stuff and decided to share it with you. So here you go, new exoplanets, tsunami on Mars, good view on Mars¬†and¬†SpaceX announcement.

Artist’s impression of exoplanet.

Thanks to new statistical method there were 1,284 exoplanets confirmed[1].
This is biggest number ever in one shot. There is of course lot of data form Kepler which observes stars for those exoplanets. You can not be sure always if what you saw was really exoplanet so you need more data. When uncertainity is below 1%, it is officially agreed that the planet is there. With this new method, lot of those uncertainities went below 1% so yes they were “discovered”. Other data was “thrown away” because the percentage went lower and generally this was nice breakthrough.[2]

For long time it was thought that Mars’s terrain was shaped by its ocean that later on evaporated. But the shoreline would be graduall which is not what we observe, rather exact opposite with many geological features along it. These features could rather be explained by huge tsunamis that were formed by asteroid impacts.

Also Mars is going to be these weeks in oposition to Sun and basically really close to Earth, on about 1/2 of AU. The closest it could be would be about 1/3 of AU because its orbit is kind of excentric. If you want to see it well, just take a telescope and with good one you should be able to see even some of its geological features. If you get to see (if it is possible for normal people) Olympus Mons, say hello from me ūüėČ

After SpaceX landed second time on the barge, Elon Musk stated that they want to land on Mars in the year of 2018, which is in two years! They have really lot of work to do so lets see where they will be in that time! (Read more here on the blog of Phil Plait)


[1]Exoplanets are planets that orbit around other stars.
[2]From the data we also know that 550 are probably rocky and 21 are in habitable zone.

How to pile up stuff

today I will write about block (in my case) or also book stacking problem. This is fascinating problem and I want you to try to take twenty cards or same blocks. Your quest is to stack them on top of each other but at the same time try to hang them over side of table as much as you can.

It should look something like this:

How much “overhang” can you theoreticly do? With twenty cards the overhand will be maximally 1.79886982857. You can only put one card on another of course.

What is this thing anyway?

Well there is nice physics and math involved behind!

Lets start with the proof why you can actually do this in the first place. Try to ask someone around “How much is it possible to overhang infinte amount¬†of blocks?” most people will probably tell you that the answer is 1/2 which is kind of intuitive, but not true as you already know if you tried the experiment that I told you to do in the beginning.

It all has to do with the center of mass. This is the place that you are trying to balance at the edge of table. As soon as the center is moved behind the edge it will fall.

For first card it is easy, you can truly get overhang of only 1/2 of the width of your block.

For two objects you can get better, actually 3/4! The first block (highest) will stay the same, it will be exactly at half of the previous one to maximize the effect. For this the center of mass will be on the edge. What about the one under that? Well there comes the problem because it combines center of mass with the one above which means that it cannot stretch so far. It carries two times the mass, lets say 2M

First block goes like this: X*M where M is the mass and X is the distance it can stretch, it is 1/2. This must equal also for the second block which carries two so there are two “masses”.

X*2M=X*M (X is different value every time)

X*2M=1/2M (because as I said X for first block is 1/2)

2X=1/2 (divides by M)


the second block has to be one fourth of its width from the table.

For third one — X*3M=1/2M …. X=1/6

Fourth = 1/8

As you continue you will find that this goes in particular series called “harmonic series”.

1/2 + 1/4 + 1/6 + 1/8…[1]

This series sums up to infinity so you can theoreticly make any overhang you want!

For the overhang of 1 you need only four — 1/2+1/4+1/6+1/8=25/24=1.04166

For overhang two you need 31!
For three you need 227!
For four you need 1,674!
For five you need 12,367!
For six you need 91,381!
For ten you need 272,400,601!

As you can see it increases pretty rapidly. 

Now just enjoy me trying to get to the best possible overhang:


[1] Harmonic series are just 2x bigger: 1+¬†1/2 + 1/4 + 1/6 + 1/8…

I used these pages as resources both for pictures and for information: 1) 2) (only first picture)

The Liebster Award

finally after 11 days I got to the nomination by: soyoungsocurious. Thank you very much!leibster

Here it goes:

The Rules:

  • Thank the person who nominated you and link back to their blog.
  • Copy and paste the Liebster Award badge to your post.
  • Nominate up to 10 new bloggers.
  • Answer the 10 questions the person who nominated you asked you.
  • Create 10 new questions to ask the bloggers you nominated.
  • Copy and paste the rules to your post.
  • Notify the bloggers you have nominated by leaving them a comment on their blog.
  1. Name and define your favorite word.
    Probably: serendipity –¬†the occurrence and development of events by chance in a happy or beneficial way.
  2. Have you ever been in love? If so, describe the experience in a sentence.
    Uhh.. well.. yeah sure. I would quote C&H:

    When you love something, you don’t just love the exciting parts… you love the boring parts just as much. People who truly love spend their lives studying the tedious little bits as well as the big flashy part.

  3. Describe your ability to dance.
    Lol, this has actually pretty interesting story behind, but from 0-100 I would rank myself something about 1/G64 
  4. What do you think about God?
    I do not think that he is somewhere, if he is than he has some far better job than interacting with me.
  5. Apart from blogs; What is your favourite site?
  6. Morning person or a night owl?
    Morning person definitely.
  7. How exciting is your life? Out of 10?
    9+0.999… (but depends on compared to what)
  8. What’s your favourite number?
  9. If everything is possible, then is it possible for anything to be impossible?
    If yes then yes.. (if God is all powerful is he able to create rock with which he is not able to move?)
  10. Finally, Which color is the dress?
    Color.jpgWhite and golden (damn)


Ok this was unusual fun, but now I have to make up another ten questions:

  1. Share your most favorite joke/meme.
  2. Star wars (yay) or Star trek (booo)?
  3. Geometry or the stuff with numbers?
  4. What would force you to go to school/work without shoes?
  5. Highest place you have been to?
  6. Link to your favorite music.
  7. What is the most strange thing you have ever heard?
  8. Favorite event in history?
  9. Your dream job when you were child?
  10. The top speed you were driving in a car (where?)?



Book review 9) 10 Physicists who transformed our understanding of reality

today I will do the review of 10 Physicists… bla bla. I started to read this book right after Christmas when I got it(but I read only one chapter finishing it last week). I actually wrote post about the first one in the list: Galileo Galilei.

Book: 10 Physicists who transformed our understanding of reality

Author: Rhodri Evans, Brian Clegg

Genre: Science, Physics

Pages: 258

Rating: 9.2/10

10 Physicists.. is a book that takes ten most important physicists in last 400 years and dissects their life and their impact.

Of course this list can not be very objective since you do not have any clear scale for something like this. I think most people would probably agree on the first four definitely:

  1. Isaac Newton
  2. Niels Bohr
  3. Galileo Galilei
  4. Albert Einstein

So sure, I would definitely from my perspective agree with those four though I was quite surprised that Bohr was rated so high. The problem is of course that most people will tend to remember Einstein and his theory of relativity but completely forget that Bohr did similar type of work but on quantum mechanics (plus many other things). Galileo may be surprising but when you consider his work on heliocentric system, well I would maybe swap him with Einstein though it is quite hard to compare people that lived in totally different times.

5.    James Clerk Maxwell
6.   Michael Faraday
7.   Marie Curie
8.   Richard Feynman
9.   Ernest Rutherford
10. Paul Dirac

In the first chapter the authors have quite good discussion about this list since they used some resources that already made similar ones. Maybe Schrödinger or Heisenberg should be there.. or Fermi?

Well we have to stuck with this one.

In my opinion the chapter that was done best was Marie Curie, I wrote about her in the last post and I must say that it was kind of thrilling, her work with pitchblende and the years that radioactivity was “adding” up in her and her husband’s body.

I guess that they could have done more work on Rutherford for example. Probably because he was so down in the list they did not want to give him so many pages but when I look back I do not remember much about him.

Otherwise I can dearly recommend this one if you do not know much about these people.

Newton who spent about the same amount of time on physics as on teology.
Bohr who was dismissed by king since he was correcting what he said.
Galileo with his: throwing stuff from Pisa tower.
Einstein who never got over the quantum theory and its probabilities.
Maxwell who finally made the theory that unified electrism and magnetism.
Faraday with his famous lectures that were attended sometimes attended by more than 1600 people.

This had to be

Feynman playing his bongos:

That is whole new style

Rutherford and his new model of atom (as always for atom models, proved wrong).
Dirac with his serious social problems but pretty cool mathematical skills.


How radioactivity was studied

today I want to write about radioactivity. It is rather new concept which is not very surprising as the process of radioactive decay is not very visible and the effects (on health for example) are not so clearly connected since they usually have long time span. Probably largest work done on this topic was by Marie Curie and her husband Pierre.

This is how radium dials looked like, cute!

Curie was from Poland. She had kind of difficult childhood since women were persecuted at that time in the east and it was hard for her to find place to study. Later on, she was able to move to Paris with her sister. There she met Pierre with whom she had two kids.

The first time she encountered with radioactivity was when she measured pitchblende [1] and uranium and how much radioactivity they ¬†were¬†“giving off”.

She expected that pure uranium would be much stronger but this was not what happened, what she found was exact opposite. Later on, thanks to this she found out two new elements: Polonium and Radium.

At this time it was not yet known that you can get pretty easily cancer by being close to radioactive stuff. Curie and Pierre were buying tens of kilograms of pitchblende to do their research and prove those two new elements since lot of other scientists were kind of sceptic about it.

In November of 1898 they extracted compound that was 900x more radioactive than uranium, you can see where this was going.

In 1902 it was announced that one decigram of radium chloride was succesfully isolated.

Four years later Pierre died when wheel of carriege run over his skull, this was because of the effects of radioactivity, at this point he was not really able to use his hands, they were pretty much destroyed by the pitchblende and his whole health was in very bad state.

In 20′ it started to be more and more clear that there is something wrong with the stuff.¬†There was actuall factory that painted dials with radium (not pure of course), this is because it glows nicely and everyone liked it. The brushes that were used for this had to be kept sharp and this was done by lips. For this work about 4,000 people were hired, the so called “Radium Girls” was a group of women that also painted for fun their nails, face and teeth, noone knows how many sacrifices this caused.


[1] Pitchblende is mineral that is radioactive since there is uranium and other heavy elements. Lot of miners in extreme conditions died because they were mining it.

Tug of war: How to win it!

last time I was writing about tug of war and how dangerous it is. In lot of people the rope may snap doing lot of damage. Also even without snaping participants may get severe burns and not only on hands. Today I will talk about the bright side of this game and how you should play it if you want to win. It is actually very interesting and I bet that most people do not use these simple rules.

Tug of war is the game in which you are trying to pull the other team over some line.

Some experience players.

It might seem that having the best muscles will win the game but actually it is only small part.

One important part is to be able to stay on one position. There are two things that will help you with this: friction and weight.

This makes sense because it will be difficult to pull huge stone on rough surface. Actually small kid will be better off with spikes on shoes than you with big muscles on very slippery ice. But muscles are still good for being able to hold well to the rope.

There is one important thing that you want to do.. you want to dig your shoes into the ground. This increases friction because what else is friction than the dirt that is connected by roots which must be ripped apart by your enemies.

So yes it is very good to be heavy and have the proper technique of digging into ground.

Also if you have players with different heights it is best to have the smallest at the end, this is because otherwise the tall players at the end will pull the small players up and disabling them in the game. You need to find the proper angle. If you get too low you wont be able to dig enough into the ground or it will be worse to hold the rope.. this effect is very strong when you are in hall and you need whole area of your shoes lying on the floor.

If you get too much high it will be much easier to turn you over and you wont be able to use your weight so much.

That is all I can come up with, make sure to create your own team, but choose the rope wisely (the best players are able to hold about 1.5x their mass)!


Tug of war: How to kill yourself!

today we had some program with whole school. It involved costumes on specific themes and also contests. One of the contests was tug of war.

Our school is fairly small compared to ones in USA, we have only 360 people. Some were not there of course so we can speak about three teams each with 100 people. There were even very small kids (10 years old) so the force was not so great, but then again.. 100 people on each side we could excert force of about 500 kilograms I would guess. At first I though the rope would snap immediately, but it was climbing rope and after I searched at home, the rope would probably survive force ten time great.. uff, we are lucky that they chose such rope!

So it did not snap.. in the first match we lost but we did not hear that it ended and thought the second team was just growing weaker so we pushed harder. At the point they were not holding it tightly at the end (it was long rope). The rope accelerated a lot and it burned their hands.. the same thing happened to us for the second time. I have little white one finger, but it is ok. When I came home I decided to search something about tug of war..


When two large teams pull the rope, it stores tremendous amount of energy. When one team just let the rope hang not very tightly the other team will burn their skin off their hands. And they are actually very lucky!

Why? Well the rope can snap, and this does very bad things because this energy is released at the same time.

Let me give you some examples how dangerous tug of war may be with lot of people:

In 1997 in Taipei there was some celebration of 52nd anniversary. Of course they had to take over 1,600 people into that game. So many people excerted force of 80,000 kilograms while the 5 centimeter nylon rope was able to withstand only 26,000 kilograms! Guess what! The rope snapped!

When snapped, the energy was released in what is called: sheer rebounding force. It tore off whole arm of two closest man. Seriously.

In 1995, first time one man wrapped the rope around his hand, it tore his hand off again. In the same year, 650 people participated in match with nylon rope. Again but worse this time, as the rope whipped back, it instantly killed 9 year old kid..

Just for you to know when someone decides to create huge tug of war match, stop him!


Check out these pages for more info: 1) 2) 3)