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Guide to Space, Planets and the Rest of the Universe

What are the Largest Moons in the Solar System?

You'll be surprised to hear that the largest moon in the solar system is not the Moon that orbits Earth. The largest moon in the solar system is Ganymede which orbits Jupiter, the fifth planet from the Sun.. Ganymede's radius is 2,631.2 km which is larger than our Moon which is 1737.5 km. In comparison, the Earth's radius is 6,371km so roughly it is a third the size of our planet.

Our Moon is the largest in comparison to the planet it orbits. Ganymede when compared to the Jupiter which is 69,911km, it is considerably much smaller comparably than our moon. Below are some moon facts of other planets.

Top 20 Largest Moons in the Solar System, Largest First

PositionMoonRadius (km)PlanetPlanet Equatorial Radius

As for what is the largest moon in the galaxy. We've not got many contenders outside the solar system so we can't answer that yet. As for the universe, we could never know what is the largest moon in the universe as we could never see and measure every moon around every planet around every star in every galaxy. You could say at the moment, the largest moon we know of in the galaxy and the universe is Ganymede.

Comments12/23/2017 11:28:17 AM

What is the Largest Planet?

The question is very ambiguous as there are a number of different types of planets, there are planets in the solar system, gas planets, exoplanets etc. So below is the largest in each group of planets.

Comments12/22/2017 4:26:45 AM

Why are there no moons orbiting Mercury and Venus?

The only planets that are in orbit round the Sun that don't have moons are the two innermost planets of Mercury and Venus. If you've ever wondered why, here are some reasons why that might be the case.

Comments12/20/2017 6:41:52 AM

Is the Earth Slowing Down?

Before the answer is given, you must realise just how slow slowing down is. It won't mean an abrupt stop today, tomorrow or the day after tomorrow. The rate at which the Earth is slowing down is miniscule, you won't even notice it. We're talking in the magnitude of millionths of a second. It would take 140 million years before the length of the day became a 25 hour day, we'd be long gone unless of course this website has been archived for life and still read.

The Moon is moving away from us at about 3 cms a year and the moon has been a stabalising effect on us. The moon was discovered to be moving away when N.A.S.A. conducted an experiment by placing mirrors on the moon and then timing how long they took to be returned. The Moon is said to be a factor in why our planet is slowing down.

At the very beginning when the Earth was very young. The Earth would've been rotating very fast, talking a few hours or so. Fast forward a few (cough, hundreds) million years to the age of the Dinosaurs. When the dinosaurs ruled the planet, the planet was rotating at a speed that is greater than it is today. A day would have been longer than 21 hours but less than 23 hours. Either way, the day for a dinosaur would have been shorter than it is today. A.B.C.

If you go back further in time, say 620 Million Years ago, the day would have been about 21 days. 620 Million years ago equates to the Vendian Period when there was life on the planet but not as we know it. In the Vendian Period, there was only microscopic bacteria and algae according to fossilised records. Berkeley

There is a theory and it is only a theory that says next year (2018), the Earth will experience a lot more earthquakes than it did the previous year. In 2016, there were 14,421 geological earthquakes. Most of those earthquakes were so minor that they were never reported in the media. The only way you would know about them if you weren't from the quake community is from the media. Being, not from the quake community, i got the figure from Wikipedia.

The Earth day is extending by 1.7 milliseconds a 100 years. If the Earth continued onto forever, the Earth would stop spinning in about 1.9 trillion years. The Sun is expected to have gone supernova in five billion years and life on Earth will have been wiped out in a billion years time when the Sun starts to turn into a red giant as it depletes it hydrogen fuel and moves into the next stage of evolution. Hopefully by that time, we'll have moved off and colonised other planets. Whats Up With That?

Comments12/20/2017 5:49:13 AM

What is the Alien "WOW" signal?

In 1977, the Big Ear observatory was listening to the stars when it recorded a signal that would later be known as the WOW Signal. The Big Ear Observatory is run and controlled by the Ohio State University in the United States. Its site is a bit basic to look at and hasn't been updated since 2008 according to a note on the page. The actual telescope was demolished in 1998 by land developers.

The signal was noticed by Jerry Ehman on August 15th, 1977 when he was pouring over the information that had been received. Jerry noticed successive values of intensity and circled them and wrote WOW on the print out hence how it got its name.

Decoding the WOW Signal

Signals were encoded in numbers and letters so that they could be deciphered easily enough. A 1 is any value of intensity between 1.0 to 1.9999 and then following that 2 meaning 2.0 etc.... etc... When the numbers were exhausted, they turned to letters so A meant any intensity between 10.0 and 10.9999 and so on up the alphabet. The "U" was the highest intensity ever recorded. There was nothing for over 35 which would have been for Z.

The signal was identified as coming from a three star star cluster that included Chi Sagittarii in the constellation of the archer, Sagittarius. This is the same constellation that contains the Galactic Centre, the supermassive black hole at the centre of the milky way.

The signal was only heard once, it was not heard of again. Scientists and astronomers all listened in on that area of space but nothing was heard again. Some joked that it might have been aliens telling us that they aren't interested and they don't want to hear from us again which would go some way to explaining why we only heard from them the once.

Aliens -The Exotic Explanation

The record set off a chain of events that went round the world. Some people saw it as being a sign that aliens were out there and they were communicating back. Our radio signals have been travelling through space since roughly the beginning of the last century and maybe an alien race had picked them up and responded. People were hopeful that it was a sign that there was intelligent life out there who had responded back to us.

Comets - The Mundane Explanation

In 2016, a new explanation was put forward, one that ruled out aliens. the explanation was that the signals came from hydrogen gas encompassing two Comets that were found to be in the vicinity of the star at the time. The comets were 266P/Christiansen and P/2008 Y2 (Gibbs). Both of these comets were discovered in 2006 and 2008 which why they were identified as a possible source back when the news first broke.

Christiansen will next come close (Perihelion) in April 2020 when Professor Antonio Paris is hoping to have a radio telescope trained on the object to see if it creates the same sort of noise as it did in 1977. He started a crowd funded venture but when it was checked, it no longer existed. Christiansen has been and gone (Jan 2017) but Gibbs is expected on or about the 7th January 2018 but probably won't be visible to the naked eye sadly. If anyone knows of any results or anything, do share by putting comments it the box below.

WOW Signal

Further Reading :- The Guardian, New Scientist

Comments12/20/2017 3:11:19 AM

Star Wars - The Last Jedi Review

*Spoilers*, before you read further, you should know there will be spoilers which if you hadn't seen the film already, you shouldn't read. This film take place immediately after the events of Star Wars VII- The Force Awakens where the Resistance had successfully destroyed the First Order's new Death Star style weapon which was in fact a hollowed out planet that drew power from a nearby star and then ejected it to destroy any solar system that they wished.

The previous years film, Star Wars - Rogue One was a prequel to the first film to come out and is not part of the new trilogy. One of the big criticisms of the previous episodic film (TFA for short) was that it was a clone of sorts to the original films in particular Star Wars IV - A New Hope with an orphan realising that he or in this case her could effect the future of the galaxy far far away. The main criticism of that film also applies to this one too.

The film is similar to Star Wars V - The Empire Strikes Back when you step back and look at it.

Don't get me wrong, I did enjoy it but it felt like Empire Strikes Back 2 rather than the prequels. Although people diss the prequels, at least they had original storylines. Ok, with the Phantom Menace, a lead character died in the first film like a lead character also died in Star Wars IV - A New Hope and also in Force Awakens.

Some of the rumours of the film that I had heard about,

Its a lot funnier than the previous films. In all, its a good film but just don't go expecting originality. The Porgs, the cute bird-like creatures don't ruin the film at all, they're just a gimmick in the film.

The Last Jedi Poster

Comments12/16/2017 11:25:40 AM

Asteroid Visitor from Another Solar System

Most asteroids that orbit our Sun are left over debris from the early days of the solar system. They were born and have lived their whole lives within the confines of our solar system. There could be some that were passing by and caught by the Sun's gravity but there are none that we are aware of. It has been announced that an asteroid has been spotted that is from another solar system. The asteroid was probably spat out from its solar system if it got too close to its star in the constellation of Lyra. Hindustan Times

The name of the asteroid is 1I/2017 U1 but it has a more common name for which is better known. The asteroid is also known as Oumuamua, a Hawaiian word that translates to messenger from afar. The asteroid was spotted by astronomers from the Pan-Starrs1 telescope in Hawaii hence its name.

In addition to the shape and path of the object, the shape of the object has also caught people interest. When you look at asteroids in our solar system, they are ball like but this one is different, it is long and thin. The asteroid is estimated at being 400 meters long which is roughly about a quarter of a mile and is said to be ten times as long as it is wide. N.A.S.A.

Oumuamua has a reddish colour and rotates about every 7.3 hours The asteroid is travelling at 85,700 miles an hour, something we can't do yet. The New Horizons space probe that went to Pluto in comparison travelled at 36, 373 miles an hour. New Horizons took ten years to get to Pluto, this asteroid if it were to travel in that direction would do it in a third of the time. As it is travelling too fast, it won't be captured by the Sun's gravity and pulled into orbit round it. At a rough calculation, the New Horizons would take 78,000 years to get to Rigil Kentaurus a.k.a. Alpha Centauri, our second nearest star. The Oumuamua would take 26,000 years. Neither New Horizons or Oumuamua are going in that direction.

Some people have considered whether the asteroid is just asteroid or is an alien craft instead. Radio telescopes were trained on the object to listen for anything that might suggest that is anything other than an asteroid and..... Silence, nothing to indicate that the asteroid is anything other than an asteroid.

If aliens were inside that asteroid, they would be hibernating or dead given the length of the journey that they would have had to undertake to get here. Were they inhibinating, the rock would have slowed down unless their target was elsewhere in the Pegasus constellation. It will reach the orbit of Saturn just over a year from when it was discovered. C.N.N

N.A.S.A. artists impression of the Oumuamua asteroid.

N.A.S.A. artists impression of the Oumuamua path through our solar system.

Comments12/8/2017 10:19:54 AM

Will Aliens be Friendly or Hostile when they arrive?

We won't know if Alien will be hostile like the creatures in V who want to enslave us and use us as a food source or if they will friendly like Vulcans in star Trek until they arrive and show themselves to the general population.

The alleged U.F.O. abductions might give the impression that the aliens are hostile by kidnapping people and subjecting them to experiments including of sexual nature. One of the arguments of alien abductions is that they've come all this way, do a few experiments and then leave.

Hostile Aliens

Professor Stephen Hawkings, one of the greatest living astronomical scientists alive today said in his Discovery programme in 2010 that aliens could well be hostile based on history. Stephen cites what happened when Europeans travelled to the Americas, it didn't end too well for the natives.

If you go back further in time to the time of the Romans, they were among the most technically advanced populations at the time. The Romans were also one of the most aggressive and expansionist, conquering Europe and some parts of Africa and the Middle East.

Aggressive aliens are more likely to create technology that would enable them to cross the cosmos to us. Hopefully not but we do have to have to prepare ourselves for that eventuality. If hostile aliens were the first to arrive, Earth will not go down without a fight. Although we haven't made the push into deep space, we're not going to be a push-over.

Too late too hide

We have been pumping out radio signals from our planet for the past hundred or so years so any intelligent civilisation that is within 110 light years from Earth will know we're here. If you'd like to know how far signals from different years have reached, its highly recommended to visit LightYear.FM.

According to the site if you pull back, the earliest signals would just be reaching 49 Librae about now. If amongst those listening were hostile aliens, they could be on their way, we'd have 100 or so years (provided from 49 Librae) to prepare, that is if we haven't blown ourselves up by then. The good news is that the site does say that the signals would be hard to distinguish amongst background noise after a few light years from Earth so if the aliens are unable to filter out our signals then we're safe. It'll also probably explain why we've not heard from anyone yet because we have not filtered the noise out from all the background noise.

Alien Abductions

The galaxy has about 100 billion stars, give or take, and to choose a star to visit would be guesswork unless you had some clue as to whether its worth visiting or studying from afar. Therefore it will explain why Alien Abductions are a relatively new thing because before our radio signals, it'd be a needle in a haystack kind of search.

The first modern day alien abduction took place on September 19th, 1961 when a couple Betty and Barney Hill driving home on a rural highway near Portsmouth, Hampshire were unable to account for two hours. After investigation, they discovered the cause to be an alien abduction and from then on, reported alien abductions increased. Quartz Media

Friendly Aliens

The opposite type to hostile aliens are the friendly aliens, the ones that want to share information, be our friends etc. The friendly alien is the type that we all hope that will come.

There's few example, in fact I can't think of any where contact between two technologically different groups ended well for the lesser. Just because history doesn't provide a case for this doesn't mean it won't be the case for alien contact.

We'd also have to be careful in case aliens pretend to be our friends like the Visitors did in V but their motives were sinister in the least.

Disinterested Aliens

Aliens might know we're here but because we're not advanced enough, they might not be interested in contacting us. Its not a new thought, its one that's been used in Star Trek. In Star Trek, Vulcans only contacted humans once humans had managed faster than light speed. Contacting Earth before we're technically advanced enough would break the first.

If the reported U.F.O. - Unidentified Flying Object are really from outer space and that they've not made real conclusive contact, it would seem that they are disinterested in making contact with us. Either disinterested or a prelude to a much bigger visit.

Government Conspiracy

Conspiracy theorists alleged that aliens have already made contact with U.S. Government and are being held in Area 51 in the Nevada Desert. They believe that a U.F.O. crash landed in Roswell and that the craft was taken away to be studied. If the U.S. Government did have the craft, how comes we've not got very far in terms of technology after years of studying.

There is also a theory that the Government has made contact with aliens but are keeping details of the contact quiet as not to scare people. The Hostile alien theory would be to not alarm the populace. The friendly alien argument is to prevent other governments from gaining the knowledge.


This might disappoint you to hear that there is no conclusion as to which way the aliens go until they arrive. You need to form your own conclusion.

Comments11/30/2017 9:22:33 AM

Where are the nearest and farthest exoplanets?

The nearest Extrasolar Planet(Exoplanet) that we've so far discovered is the planet that is orbiting Proxima Centauri. Proxima is a small red dwarf star in the Centaurus constellation in the southern hemisphere. The star is not visible to the naked eye, you need a telescope to see it.

The star is roughly a mere 4.1 light years away from us, an astronomical neighbour. A light year is the distance that light travels in a year which is approximately 5.9 trillion miles or 63 thousand times the distance between the Earth and the Sun. We currently don't have anything capable of travelling that distance or has been there so what we know about is guess work and calculations.

The planet is close its star and orbits very quickly, in fact, it takes about 12 days to orbit the star. We don't know if there is life on the planet but its been calculated to orbit the star within the Goldilocks Zone, the area of space which is neither too hot nor too cold for life to exist. Any images you might see of the planet including though se on this site are artists impressions and not the real thing.

The farthest exoplanet that we may have discovered so far exists in the Andromeda Galaxy. Its not even in the Milky Way, our home galaxy. The Andromeda Galaxy, located in the constellation of Andromeda is an estimated 2.537 million light years away according to Google. The only way we could ever get there is to use a wormhole or use Doctor Who's spaceship, the Tardis. The discovery was made by micro-lensing, in other words studying the light rays coming towards the Earth.

If you thought the exoplanet in Andromeda Galaxy might have made you short-changed and you was looking for something a bit closer, say in our galaxy. One of the farthest is OGLE-2014-BLG-0124L which is located near the Galactic Centre of our galaxy about 13,000 light years away. It is in the constellation of Sagittarius. Caltech

The record for the farthest exoplanet will probably be beaten and this article will be out of date one day. The nearest exoplanet will probably always be Proxima Centauri b unless we discover a Rogue Planet, that is a planet that doesn't orbit a star.

We're here because of an evolutionary fluke that kick-started complex life on this planet by the binding of two simple cells. The chances of this happening elsewhere is very large. It is quite possible that we're alone in the universe or just alone this galaxy. We've not discovered life anywhere yet so anything is possible. It might be that we should be looking at other galaxies for life, one intelligent life-form per galaxy. Daily Mail

Comments11/29/2017 7:17:22 AM

Largest Exoplanet in Relation to Star Discovered

Scientists have been finding Extrasolar Planet(Exoplanet) left, right and centre across the galaxy. Scientists have even discovered a planet in orbit round the nearest star to us, Proxima Centauri. You'd now think that nothing would catch many people's attentions. Now along comes NGTS-1b, an exoplanet named after its star.

It is a Hot and Super Jupiter. The planet orbits close to the planet and orbits in 2.6 Earth days and therefore it is quite close to its star, in fact, it is only 3% of the distance between the Earth and the Sun. The star is a red Dwarf Star, a star type that comprises of up to 70% of stars in the galaxy. The dwarf gives it away, it is a small star, much smaller and cooler than our own sun.

An artists impression of NGTS-1b

An artists impression of NGTS-1b, credit: University of Warwick, Mark Garlick.

Although exoplanets have been discovered around small stars such as Trappist-1, what makes this unique is that the exoplanet is nearly as big as the star it is orbiting. The planet is bigger than our biggest planet, Jupiter. There probably no chance of there being any form of life on the planet because it is too close to its star.

The team that discovered it was the University of Warwick in the U.K. It was discovered using the Next Generation Transit Survey (NGTS) in Chile from where it got its name from. The star is located about 600 light years away in the constellation of Columba the Dove.

Further reading : C.B.C., Fox, National Geographic

Comments11/5/2017 8:52:00 AM
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