The Universe is enormous

Hi,
I was thinking what topic should I mention today and remembered that the Universe is huge, and it is so huge that we completely underestimate it (at least I think that I still do).

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First I will turn towards our planet, the Earth.
Here the biggest misconception is the size of Africa, you see the problem is that in most maps of Earth which you will see is Africa in the middle. If you know little about geography you know that there is no way to perfectly put our planet to scale on map. There are some ways which will be more accurate than other but most of the time Africa is going to be smaller than other continents. 

OK, now compare this map above with the scale on your home atlas, Africa is going to look tiny probably with Greenland, Siberia and Canada huge.

Now look at the picture of Earth and Moon distance, they are so little, Earth would be able to fit there so many times!

Now, seriously, look at this amazing page: THIS You start with Moon which is wide as one pixel. Next you will see Sun which seems to be pretty huge. Now if you click the speed of light button you will start to move slowly to right. Oh my god, the speed is so awfully low!

On top of page you have the bar with planets so you can click on them and ride from one another, remember, it is TO scale, and after you drive through whole map they say: You would have to travel 6,500 more maps like this to get to something.

This is huge, we are from Sun only 150,000,000 km.

OK´, Sun is small, lets see why:
1st picture shows that Sun is big:

2nd picture, well Sun gets little smaller:

3rd picture is actually a whole different story:
Now here is the last to compare it all, with little bonus of Canis Majori:
Ok but all of this stuff is so freaking small compared to whole Milky way! The radio signal from Earth which traveled for tens of years is not even visible on map of Milky way!
You can fit Sun 1420 times next to each other inside VY Canis Majoris.
And  you can fit Earth like this 109 times.
This means that you can fit Earth 157,780 times inside VY.
The diameter of Milky way is roughly 140,000 light years. Where one light year is 9,460,730,472,580,800 meters.

This is 741,669,055,548 Earths for diameter of Milky way. 2,540,000 light years is the distance to Andromeda galaxy, the closest galaxy.

Virgo Supercluster has 110,000,000 light years. Easy. On the next picture from @HighTechPanda , you can see the comparison of largest galaxy to Milky way, enjoy!And last, observable universe has 93,000,000,000 light years in diameter.

Still so underrated.

Dragallur

Africa picture

 

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Planet classification

Hi,
here it comes, here it goes. Today I will write about planet classification since I want to start to write about dwarf planets. This post will be little similar to Stellar classification but you will see that for planets there are not those classes for size differences. The most important thing is of course to know what is planet and what is not, which I will explain.

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Ok in the year of 2006 International Astronomical Union anounced that Pluto is not a planet. It`s been almost ten years but I still know people that can not get over it. I know this picture is sad (and not to scale).

For now the definition go as follows:

Planet has to be orbiting Sun
Have to be generally spherical
Has to have enough strong gravity to clear its orbit.

So the thing is that Pluto can only check first two criteria but not the third so such a object is called a dwarf planet.
Also you can see that planet is only object that is orbiting Sun which as it seems is not any exoplanet. This means that those 2000 planets that we found are just a huge objects, but for the official definition they are not planets either. And.. because they are so far away, it can not be known yet if they are spherical or not.

You can see that those definitions are not very good but luckily one guy on some conference proposed new definition which is not yet agreed to be new one but anyway International Astronomical Union will have to make a better one which will be probably very similar to this:

Planet has to be orbiting at least one star or the remains of one. (So yeah, stuff that is orbiting white dwarf is still a planet if it meets the other criteria. Read about multiple star systems)
Planet has to have a clear path to itself. (Sorry Pluto.)
Planet has to have mass lower than the mass of Jupiter. (This is good so we dont accidentaly name brown dwarfs as planets.)

Now we know what are planets. Lets move what are dwarf planets. Those are the objects that are not able to satisfy the third rule, their orbit around Sun is not clean. Dwarf planets are: Ceres, Pluto, Haumea, Makemake, Eris and Sedna for example.There are some other candidates also.

There is type of objects that are called minor planets. Those can be at the same time dwarf planets, like Ceres. The number of minor planets is increasing by very large amount every month. Only few of them are named, large part is numbered and there is  rest for which we dont even know exact orbit. Together there are almost 700,000 minor planets.

I did not find exact definition but minor planets should be those that are orbiting Sun, that is about it. They dont have to have any particular size, shape and their path can be trafic jam of asteroids. Actually yes, the asteroids are minor planets and also all the trojans and so on.
Above you can see all the types of objects that can appear in our Solar System except Sun.
Thats about it, I will definitely make post about or more about asteroids, comets and of course I will be continuing with moons.

Dragallur

Pictures are from wikipedia pages: IAU definition of planets, Minor planets and Dwarf planets and the first one is from this page:

Planets of our Solar System: Saturn

Hi,
again I am returning to series about planets, this time it is Saturn. Saturn or Kronos in Greece was titan in greek mythology, son of Uran and Gaia.
Saturn is second largest planet in our system. It is also gas giant so you wont find there any solid surface, but there is solid core in the middle.
Kronos orbits in 9-10 AU from Sun which makes him rotate 29.46 years (that is why is was mentioning in post about transit photometry why you can not find such exoplanets by this method).

Saturn is the most flattened planet and it is because of really fast rotation (day is 10.5 hours long) and because of mettalic hydrogen which is just around the core (you can flatten much easily something liquid then solid).

Also Saturn is the least densest planet. It´s actually so not dense (what is opposite of dense?) that it would flow on the water, its density is: 0.687 g\cm3. This also does not help its gravity which is 0.91 of Earth´s on the equator.

On the northern pole there is this hexagonal “structure” which was for the first time with rest of the planet fotographed by Voyager 1 and 2 (you can see it one the gif). It is assumed that it is created by specific flow of gases and their interaction.

In the year of 2010 there was observed enormous storm running around whole planet, it had to have about 300,000 km.

Now as you can see on the first and third picture and as you surely know Saturn of all four gas giants has the biggest planetary rings. They could be made by some huge asteroid torn apart.
Those rings are 250,000 km from one side to other and only 10 meters high!

There is actually more of them “d” is the closest to Saturn, then comes “c”, the thickest “b” and “a” and “f”. There are two main gaps: Cassini division which is named after our satellite orbiting Saturn and Encke named after the guy who was observing rings.

Saturn has 62 moons as far as we know. The largest is Titan and I will make sure to make posts about some of the most important one´s and probably I will even write post only about the rings.

Only one last interesting thing: when some of the moons are little bit out of normal orbit, rings start to make “waves” which can be kilometers high.

Dragallur

Sources of data and pictures and some more stuff to read about:
https://en.wikipedia.org/wiki/Saturn
https://en.wikipedia.org/wiki/Cronus
http://www.wired.co.uk/news/archive/2013-09/04/saturn-hurricane-water-ice
https://en.wikipedia.org/wiki/Rings_of_Saturn#Encke_Division
+ amazing video by Crash Course (Saturn)

Planets of our Solar System: Jupiter

Hi,
lets see what we got here, the biggest planet of our Solar System into which all other planets would fit with space to spare. It is Jupiter, named after Roman god of gods or Zeus in Greece mythology.

It is nine times wider than Earth but its mass is 1300 times larger. It is the fastest spinning planet, one day on Jupiter is 10 hours long which makes him 6% less like a circle. Mean distance from Sun is 800,000,000 km or 5.2 AU.

Jupiter is the closest gas giant, which means that he has no surface only thicker and thicker poisonous clouds with various gases. Darker parts are called zones and lighter belts, both of them are rotating in opposite directions. This process is powered by the internal heat of planet (Jupiter loses heat more than he receives) and by fast rotation.
On the picture you can see The Great Red Spot, it is on left of southern hemisphere. That is storm which lasts for decades but now we know that it is shrinking and eventually it will disappear. But for now it is stronger than any storms we ever hope to have on Earth with winds of over 500 km.

When we would dive beneath its deadly atmosphere we would appear in ocean of metallic hydrogen (hydrogen atoms that are sharing their electrons which makes them act as metal). Underneath we are not really sure but there can be solid core of metals and/or rocks.

While Jupiter is really large it is not even close to becoming star, it would have to be 12 times more massive. There exists a theory that Jupiter helps Earth by changing the pathway of comets and other stuff in space but on the other hand it could work in the same opposite way, but still we are not dead yet.

Juno (Hera) spacecraft is right now heading towards Jupiter. In the half of 2016 it will arrive and for 15 months it will collect the most accurate data that we ever had because of its close orbit.

For now there is 65 known moons orbiting Jupiter and I will definitely mention some of them in the future.

Dragallur

PS: be sure to check out Mercury, Venus and Mars!

Planets of our Solar System: Mercury

Hi,
here it is, thing I wanted to do a long time: first post about first planet of our lonely Solar System.

Mercury, it is the first and closest planet to Sun. It means one simple thing, it is freaking hot.. but not always.. actually it is not that hot but you would die there, that´s for sure.

Mercury has second highest density of planets in our SS. Right after us. It has pretty big metal core and gravity there is almost the same as is on Mars which is much larger.

The name is same as for Roman god of messengers and travelers. It has strangest orbit of all planets, most elliptical since when you look on other planet´s it looks like circle. Here Mercury is moved by great distance: in Perihelion (close to Sun) it is 0,307 AU away but in Aphelion 0,467 AU. Also orbit is declined by 7° from Earth´s orbit.

This huge piece of rock has really weak exosphere and also really weak magnetosphere. Magnetosphere is probably so weak because axis of Mercury is only 0,1° declined while our is 23° or so… There is no stable atmosphere because Mercury can not hold it from solar winds.
Solar winds are so strong here that they are probably eroding planet´s surface.
Even that there are extreme temperatures so one would except that all water would evaporate but in cracks on poles there are actually tons of tons of water ice!
On the side turned towards Sun can be over 450°C while on the other there is below -170°.

Mercury is not geologically active. It´s year lasts 88 days and day 58 Earth days. This and elliptical orbit create really strange event. When it is about midday on Mercury, Sun stops and for few days it goes backwards and then again it goes in the right way.

Most craters are named by artists and one of them is named Tolkien. There is also one of the biggest craters in whole solar system with 1600 kilometers across and it is called Caloris Basin.

First satellite which mapped the surface was Mariner 10 but much better data was send by Messenger.

Dragallur