Lovely Jupiter

today I want to do a short rewrite of some posts from NASA page about things happening lately in space, simply to understand and remember them better, makes sense huh?

I have got three things, Van Allen Probes, OSIRIS-REx and Juno (I am saving that one as last since it is simply best).

Van Allen Probes are two satellites orbiting Earth in 9 hour intervals (2 000 miles per second). They celebrated their 5th year anniversary. Such a satellite must be hardened against radiation, otherwise the high energetic particles would destroy its electronics. Throughout its life, it discovered for example that there can be 3rd radiation belt around the Earth.

I already wrote about OSIRIS-Rex before. It is rare mission, first of its kind because it will optimally return samples of the asteroid Bennu back to Earth. On September 22nd, it will pass couple thousand kilometers above Earth that will speed it up so that it does not have to use so much fuel. They had to make sure that the spacecraft does not hit some other satellite that is in the Earth’s orbit, it would be quite sad if this couple hundred-million-dollar project failed even before the landing (I guess it must be in this magnitude).

If you read my blog you know about the spacecraft Juno and that it got close to Jupiter (and started the mission after the long flight). I guess I do not need to say anything when I share those (color enhanced) pictures from the eight-close approach.Juno’s Eighth Close Approach to Jupiter


Sources are just those three NASA pages.


Europa Multiple-Flyby Mission

today I am going to write about proposed mission to investigate Europa.

Europa Multiple-Flyby Mission is a plan consisting of orbiter and a lander directed towards Jupiter‘s moon.

The reason why to choose Europa is quite clear. There is probably liquid water under its surface and if one launches such a thing, it might get public’s attention.[1] (Which might be now more important than ever considering how Trump wants to cut down NASA’s budget especially on the most important thing that they do: Earth’s climate monitoring.)

First of all the orbiter, which would be launched in the next decade, would learn as much as it could about the surface of the moon, Jupiter’s magnetosphere (see later), weird water

Composite image of Europa superimposed on Hubble data

This is two images of course. The original does not have the Europa in middle but only black spot. You can see the plumes on roughly 7 o’clock.

plumes and so on. There are 9 instruments together planned.

Instruments on those orbiters are able to collect data faster than we can receive it. This is because there are more mission that need attention of our receivers. Those are not some small receivers but specialized ones and all missions have some time to send information. For example New Horizons, just from its flyby of Pluto kept sending data for some 6 months.

In case of Jupiter oriented mission this might be a problem because Jupiter has extremely strong magnetosphere which will probably damage the instruments in matter of few weeks. This way it is best to get close to Europa and then get away as soon as possible and send the data later. This can not be done for the lander so it really lasts in matter of days. (Yes, it is still a problem even if you cover your equipment under 150 kilograms of titanium as is planned!)

The lander is thing planned even further into future, around 20 years or so. Much can change and we will see what the priorities are at that point.


[1]People will probably get quite excited by mission promising founding signs of extraterrestrial life.

Juno has some real party instruments!

as I promised, today I will write about instruments that Juno has acquired for the journey to Jupiter. Also I wont post anything for something like two weeks again because I am going with my mum and sister to Poland on vacation. After that I will be few days at home and then I will go to Germany for one year (of course I will start writing again at that time).

Juno is very well prepared to gather some data, here are all the things that Juno is capable of:

Gravity measurements

To measure if Jupiter has solid core or not scientists are going to measure Doppler shift of radio waves transmitted back to Earth. The changes of gravity from computed should be from either storms if they go very deep into the atmosphere and/or changes of density and surface of the core if it exists.

JADE – Jovian Auroral Distributions Experiment

Those are three detectors that each covers 120° + one special detector that has 270° view. This experiment is trying to observe the auroras of Jupiter by measuring the charged particles that create them.

JEDI – Jupiter Energetic Particle Detector Instrument

Right this does not correspond to the acronym but you know.. Jedi 😉

This experiment is similar to JADE except that it consists of only one detector and detects particles with lower energy.

JIRAM – Jovian Infrared Auroral Mapper

Again this one watches over auroras but also it makes infrared images of the atmosphere.


This is somewhat unnecessary camera that is going to collect pictures for public. There was even voting for what pictures it should take because it wont have so much time. As I said in the last post it is going to have some cool resolution but we will have to wait about month for it.


Juno also has magnetometer that will measure the strength of the magnetic field and its other attributes. It is quite big instrument with 3.6 meters height.

MWR – Microwave radiometer

Such thing was not used before on Jupiter so it could be huge surprise what we will see in microwave radiation because that is exactly what wavelength this instrument measures.

Ultraviolet Imaging Spectrometer – UVS

This one will watch Jupiter in ultraviolet. Here nice target are again the aurora because they are much easier to watch in UV especially because you can do it even during day.


Waves are basically two antennas which are about 3 meters long and then one smaller electronic device. This instrument is going to measure the interactions between magnetic field and atmosphere. The smaller device is mostly wire, turned 10,000 times around some bar.

From all of this it could seem that Juno is going to measure only magnetosphere and auroras though this is simply what you can do without needing to crush into the planet. (Which will happen anyway though Juno wont survive of course). All of these things are quite observable from far away and yet they can tell you a lot about the planet.


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

Juno is right at the party!

wondering what to write about today I decided that best would be to catch up with the mission Juno which is going to explore Jupiter.

Juno Reaches Jupiter

This is doodle by Google which shows the excitement of the scientists as they watch the signal from Juno coming back after it started to orbit Jupiter.

So it has been basically 5 years since NASA launched Juno (2011 August). This satellite is the second one after Galileo that is going to orbit around Jupiter. Most of others were just on flyby to other places and Galileo kind of broke.

Artist’s impression of Juno.

Juno mission is going to last for about 1 and ½ of a year. This seems kind of short time when you consider that it took alone 5 years to get there. SciShow Space said that it is because NASA does not want to risk getting Europa spoiled with ANY organisms from Earth though I think that this is nonsense and that NASA just does not have enough money which is something I will get to in another post.

What will we get? Well hopefully we will learn more about formation of Jupiter and whole Solar System, this is basically the main purpose but priority is also the gas of Jupiter and its magnetic field. We wont get probably any pictures of the moons because they are not part of the mission and they would be very small. At one point the JunoCam instrument will have a great resolution of Jupiter, about 15 kilometers per pixel. This is something amazing since Jupiter has about 140,000 km in diameter.

Right now Juno is on what is called “capture orbit”. Those are two 53.5 days long orbits which will then lead to 14 day science orbits where the real data is going to be harvested.

Everything about the mission is quite planned.

Juno is also the furthest man-made satellite that is powered only on solar panels. At the distance where it is, there is only 4% of sunlight compared to Earth.

Next time I will cover what tools Juno carries.


Moons of our Solar System: Thebe

continuing in the promised series about moons I will today cover the satellite Thebe, this time I even have some “high resolution” pictures so keep on reading!

There are few huge craters on Thebe. (largest is Zethus with diameter of 40 km)

Thebe is another Jupiter‘s moon. It is quite smaller than Amalthea, with 100 kilometers as mean diameter. It was named for Greek nymph, in both stories I found, she was lover of Zeus (yet again) but in one she was also the daughter of Egyptian king.

It is quite similar to Amalthea, again it is tidally locked, which means that one side always turns toward Jupiter (this is also true for Moon). The surface is probably red what you can not see on black and white pictures of course. We can estimate its mass only based on the similarity with Amalthea, the value you will get is roughly 4*10^17 kilograms.

For the first time its image was taken back in 1979 by Voyager. Later, Stephen  P. Synnott found it on one picture. Four years later the name we use was first used.[1]

The fact that it is blurry wont help you much.

The above picture is the first sign of another moon, but watch out, this one is only shadow.

In background you can see some huge storms on Jupiter.

Another picture of Jupiter but this time Thebe is really visible! (Yeah it is not just filth on you monitor).

Finally, Jupiter has faint rings. These rings have to made up of something. Usually rings are created when some rocks are ripped apart by tidal forces. Also they can be fed over long periods of time be debris that leaves some moons.

Thebe has one very faint ring which is created by the second method. It is three times fainter than the ring of Amalthea which is very faint too. It has diameter of 65k-113k kilometers and it is not so thin (8400 km) as the Saturn’s rings which are even only several meters tall.


References: 1) 2) 3) 4) 5) 6) 7)

PS: the second and third pictures were taken from the same site and official permission should be needed only for commercial purposes, which is not me.

[1]S/1979 J 2 was the original name, though I did not decode it it probably means S=satellte 1979=the year it was found J=Jupiter 2=probably second in row with this designation.

Moons of our Solar System: Himalia

it has been about 4 months since I last posted about moons. The last post was about Amalthea (pretty cool name huh?). I thought that maybe I should resume some of the series so lets see how it will go. (its mostly astronomy blog so no wonder that these things are here.)

If I count right, Himalia has 29 pixels!

Last time I was talking about Jupiter’s moons so I will continue with those. Today the topic is Himalia.

As you could guess, this name is connected to Jupiter (Zeus in Greek mythology). Most of the time all the people (moons) are lovers of Zeus and Himalia is no exception, she was the nymph that brought 3 sons to Zeus, those were Spartaios, Kronios and Kytos.

Though I found that she is good for watching I highly doubt this since the apparent magnitude (how bright it is) is only 14.6 which makes it almost as visible as Charon, the moon of Pluto (15.55).

Himalia is the largest irregular satellite of Jupiter. To be irregular satellite means to be formed somewhere else and be captured later on by the planet. Such moon has highly eccentric orbit which is also inclined and even retrograde. She orbits much further from Jupiter than the other moons I talked about. The distance ranges from 11-13 million kilometers! This is one 15th of the distance of Earth to Sun which is quite a lot for a moon!

Since there are many other objects around Jupiter like Galilean moons that are easier to study (also more interesting) not many missions studied this piece of rock. It was discovered on 3rd December of 1904 by Charles Dillon Perrine. We know some things from spectroscopy, it is similar to C-type asteroid which means that it contains minerals with

Not so good either

water though otherwise such an asteroid is pretty dark. While Himalia is small compared to planets, it has masss of 4.19*10^18 [1]. It’s diameter is not very clear because the closest pictures were taken millions of kilometers away. There are basicly two pictures of this moon, one which you can see above is by Cassini-Huygens and second is by New Horizons (on the right).

It was thought that Himalia has something to do with the disappearance of other even smaller moon Dia when it disappeared in 2000. Dia was luckily found in 2010 so Himalia is innocent.


[1] This does not mean that Himalia is heavy in Solar System, Earth has roughly 6*10^24.

Moons of our Solar System: Amalthea

today I will write about another moon of Jupiter. This is surely not known to larger community because it is much smaller than the Galilean moons. I would like to say that it is beautiful as her name which I really love but the images of its surface are kind of blurry.

Totally beautiful:

Amalthea PIA02532.png

Amalthea was discovered in 1892 by E.E.Barnard (that guy after whom Barnard’s star is named after [1]). What this tells about it? Well it has to be quite big because back then the observations were not so good yet.

It was named after Amalthea, the Greek nymph who nurse Zeus, so once again it has to do with the planet it orbits.


Amalthea if part of one ring of Jupiter, this one is called Gossamer ring. It is orbiting as 3rd satellite from Jupiter as far as we know, at the distance of roughly 181,365.84 kilometers, there is practicly no eccentricity in its movements and it take almost 12 hours to complete one spin. Some of those strange features can be explained by the moon Io.


When I said that it is not small I really meant it: 250 x 146 x 128 kilometers does some stuff. It does not have any geological activity as Io so its surface is heavily covered with craters.

There are some huge ones on its surface which were surely made by violent impact probably changing the orbit of the moon a lot, you can see them on the picture.

Otherwise there is not something too special observed about the surface of the moon, it is cold place but we still have a lot to search there.

The ring in which she orbits is made from her because Jupiter is reaping dust from its surface.

When person would stand on its surface it would see enormous Jupiter over 40° of sky. The gravity there is not so strong compared to our Moon but still great: 58m/s. Jupiter would also be very very bright, 900x brighter than Moon when it is full.


[1] Check out my page about Daedalus mission!



Moons of our Solar System: Io

it has been couple of posts since I last wrote about moons ofour solar system. Today I will write about the last Galilean moon: Io.

Pravdivé barvy pořízené během cesty sondy Galileo

Io is kind of hellish world. With extreme temperatures and extremely poisonous chemicals, everywhere. Still it has suprisingly beautiful colors and this piece of strange rock is very important component in Jupiter‘s system, lets see why.

Io was with the rest of Galilean moons found out first by Galileo and Simon Marius who gave her the name: Io which was pristess of Hera. She was also Zeus’s lover as it happens frequently.


The picture which is above is taken in true colors and there is yellow red and brown because of certain element. You probably remember this one: sulfur.

There are also various kinds of silicates, this is stuff that contains silicon. Otherwise sulfur dioxide and all other various compounds.

What really suprised scientist when they saw the surface for the first time was that there were and are not many craters. They wanted to date how old the moon is but it surpised them what they found. The surface is in this feature similar to Earth. There are almost no craters because of its geologic activity (othewise rare) which transforms the top layers all the time.

There are more than 400 active volcanoes. Io, is the most geologicly active thing in whole
known Solar System.

There are roughly 150 mountains on the surface ranging to even higher heights than Mount Everest. There are not very steep because there is a huge erosion causing stuff to smooth out. Those mountains were created by the push of the litosphere going down while some parts went up. There are also special features called paterae. They are similar to what on Earth we call caldera which forms as you can see on the right.

This particular picture shows the formation of Crater Lake in state of Oregon, I have been there and I must say that it is something extremely beatiful!

Otherwise the surface is cold, about -143°C but there are some areas around volcanoes which are heated up to even 17°C.


For a long time humans just saw Io as a point in the sky with magnitude of 5. It took the first probes to actually observe something about it except roughly the color.

Pioneer 10 and 11 launched in 1972 and 1973 respectively were the first probes to collect some data.

After that famous Voyager 1 and 2 did another flyby collecting even more data followed up by Galileo and New Horizons.

Orbit, size and atmosphere

The orbit of Io is in resonance with Ganymede and Europa as I already mentioned before. This creates tidal heating through friction causing all this geological activity. Io orbits as fifth moon from Jupiter but it is the closest one of the Galilean moons. This means roughly 421,700 kilometers and one orbit takes 42.5 hours, the moon itself does not rotate because it is tidaly locked to Jupiter.

Io is just a little bigger than Moon, by about 5% which means diameter 3642,6 kilometers but far greater mass (+20%). Io is very dense moon.

There is even atmosphere but it has the pressure of about one billionth of our atmosphere. It is mostly composed of oxide disulfide. If some probe would land there it would not be able to use parachute and it would not need heat shield to prevent from burning. To slow down, it would have to use its rocket nozzles.

What is really interesting is that it interacts with Jupiters magnetosphere which takes out about one ton of material from Io. Io also works as giant generator creating electric field which would kill human in matter of minutes with the power of 400,000 volts and 3,000,000 ampers.


Io picture
Caldera picture

Moons of our Solar System: Ganymede

Hi,Největší měsíc Sluneční soustavy Ganymede
here it comes here it goes, the post about Ganymede.
Ganymede was in Greece mythology really beautiful guy. Zeus decided that he wants him on the Olymp so he made him waiter. Thats about it, Ganymede is only Jupiter`s moon that is named after male.

With other Galilean moons Ganymede was discovered by Galileo in the year 1610.

Now for some facts, Ganymede is the largest moon of our Solar System. It is so large that if he would orbit Sun instead of Jupiter he would be considered planet. Ganymede has greater volume than Mercury, but is not so heavy (has about half of Mercury`s mass).
Still even with such a low density (1,936g\cm3), he is twice as heavy as Moon.

Ganymede is orbiting Jupiter with really small excentricity even that there are other moons which could be distracting his orbit. Orbit distance is about 1 million kilometers and he is able to go around every seven days. As other moons he is tidaly locked to Jupiter.

When it comes to interior of Ganymede it is very interesting. As you can see on the surface is ice crust (and quartz rock). When you check the first picture you can see that there are mainly two shades, lighter and darker. Lighter seems to be newer and without impact craters. Same as on for example Moon or Mars, some tectonic activity probably smoothed everything out.

Right under ice crust there is REAL liquid water! It was found by Hubble Space Telescope when astronomers found out that aurora of Ganymede should be “changing|waving” by about 6° (caused by Jupiter magnetosphere) while it does only by 2° which is by salty ocean which has huge impact because it is electricly conductive. This ocean`s volume is larger than of Earth`s volume, it is 100 kilometers deep.

Ganymede is the only known moon to have its own magnetosphere. It is created by convection of liquid interior of Ganymede (it was first discovere by the satellite Galileo). Convection is process which for example occurs in ocean when cold water goes up where it heats and then sinks again, then its temperature drops and whole process repeats.

Ganymede was created in the accretion disk of Jupiter when whole Solar System began to form. Because he was formed closer to Jupiter than Callisto, liquid and solid parts more easily separated. It took 10,000 years to form him. Example of accretion disk is on the right.

Ganymede, Europa and Io are in orbital resonance. This means that are in some (1:2:4) ratio of orbits. For one Ganymede`s rotation there are two rotations of Europa and four of Io. I found gif of this on wikipedia and I could watch it whole day (not to scale). This resonance also causes heating of their interior because of friction.

First mission to which saw Ganymede from close look was Pioneer 10 and 11. Then Voyager had much better look and finally Galileo (and then New Horizons). For the year of 2020 is planned another mission which would orbit Jupiter.


plus wikipedia pages like Ganymede, Orbital resonance..

Moons of our Solar System: Jupiter´s moons, Prologue

today I will continue to write about moons. Now I will be stucked on the moons of Jupiter for while since it seems that there are about 8 worth a separate posts so this will take some time and today I will try to introduce them.

So for now there are 67 confirmed moons of Jupiter which is most in the whole Solar System. They are named after Jupiter/Zeus´s lovers daughters etc.
After while we run out of those names so we started to repeat them with little changes like: Ganymede>>Ganymed
Callisto>>Kallisto and so on. All moons of Jupiter are tidaly locked.
Those moons are in different groups and the most important are Galilean moons.

Galilean moons are four moons discovered by Galileo Galilei. He discovered them in the year of 1610 even that there are some informations saying that before him chinese found them. What is sure is that independently day after Galileo, Simon Marius found them too and he was the one who gave them the names we use now (before we called them Jupiter I, Jupiter II…).
From left to right you can see on the picture: Io, Europa, Ganymede, Callisto. All of them except Callisto interact through gravitation, they heat each other´s interior through friction.

On the right you can see Galilean moons from Celestia with their orbits. The pie graph shows mass of moons.
Second group really worth mentioning is Amalthea group (beatiful name). Those are inner satellites which orbit really closely to Jupiter.
Members of this group are: Amalthea, Thebe, Adrasthea, Metis.

Amalthea PIA02532.pngBelow you can see picture of Amalthea.

On last picture are the other moons with their irregullar orbits, there arises a question how much should they be considered moons when they are so small.


Pictures taken from: —> here you can find table of all Jupiter´s moons.

Crash Course video Jupiter´s moons