Should I be scared?

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There are a lot of stories circulating the web claiming that Ison is a threat to us, these stories are simply not true!
On this page we will examine the rumors and separate the facts from the fiction.....

Ison is going to hit earth!

No it wont. 
Simple as that really! 
Hundreds of thousands of astronomers all over the world are watching and tracking Ison though the solar system, we know where it is, where its going and when it will be there.
All of us are in agreement that Ison WILL NOT hit the earth, it wont even come close! 
Now the conspiracy theorists will be screaming cover up at the top of their voices, but if there really was a comet on a collision course with earth it would be impossible to cover up! There are simply to many people watching it for any government or organisation to cover it up.  Don't trust us, fair enough, but let me put it like this........

I can see Ison, I can track Ison, if I thought for just one second that there was any chance what so ever that Ison could strike the earth, would I be wasting my remaining days writing this? 
NO!!! I would be digging the deepest bunker I could, as fast as I could, and so would every other astronomer on the planet..... the day you see a guy with a telescope in one hand and a shovel in the other, that's the day to panic!

The closest Ison will get to the earth is 64,000,000 km (39,900,000 miles),  "that's nothing in space terms!" I hear you cry, but distance is relative. If we are measure the distance between galaxies for example the 64 million kilometers is nothing, but when talking about the distance of a comet from earth its huge. Now its hard for the human brain to deal with numbers and distances like this, even astronomers cant comprehend it so lets scale it down.

Ison has a diameter of 5km, that is 5,000,000mm
The earth has a diameter of 12742km that is 12,742,000,000mm

If Ison was the size of a grain of sand, the earth would be the size of a small truck in comparison. Ok so how far apart are the truck and grain of sand? 
That tiny grain of sand is a whopping 12.8 km (7.98 miles) away from the truck!
Yes Ison will get close if you compare it to the distance between us and the next galaxy, but by that measurement so is Mars or Jupiter! Paris is "close" to London if you compare it to New York, but try walking it and then tell me they're close!  
Remember distance is relative!

Ison is going to crash in to the sun!

No it wont, well not really, and even if it does it wont do any harm, let me explain.....

As Ison gets close to the sun it will start to melt, (remember comets are just giant cosmic snowballs) it is this melting which will cause the tail to expand. At the same time the gravity of the sun will exert massive forces on Ison as it whips around the sun. Now we in the white coats are not sure if Ison will survive this, the combination of the melting and the gravity could literally rip Ison to pieces and pull the remains in to the sun.
If this does happen what would be the result? 
Answer: Nothing! Ison is a ball of ice, the sun is a giant ball of fire!

Remember the grain of sand comparison:
Ison has a diameter of 5km, that is 5,000,000mm
The sun has a diameter of 1,391,000km that is 1,391,000,000,000mm

On this scale the sun would be represented by the London Olympic stadium! 
So imagine throwing a piece of ice the size of a grain of sand in to a bonfire the size of the Olympic stadium, burning at 5500 degrees Celsius. Not much will happen, well not to the bonfire anyway....

Ison Will pull the earth out of orbit!

No it wont.

Earth is held in orbit around the sun by the suns gravity. Gravity is a force that is dependent on 2 things, mass (the amount of matter measured in kg) and how close the objects are to each other.The more mass an object has, the stronger its gravity, basically size matters! We've all seen video of astronauts on the moon, they can jump much higher than they can on earth because the gravity on the moon is much less than on earth. The reason there is less gravity on the moon is because the moon has less mass than earth. Now Ison is tiny, the moon is small, the earth is big, and the sun is huge! But what sort of figures are we talking about?

Mass of the sun:      1,988,920,000,000,000,000,000,000,000,000 kg
Mass of the earth:                 5,973,600,000,000,000,000,000,000 kg
Mass of the moon:                     73,600,000,000,000,000,000,000 kg
Mass of Ison (estimated):                                  3,175,146,590,000 kg

So as you can see there is a massive difference! The mass of the sun is a colossal 626,402,575,006,781,025,502 times greater than that of Ison!
Ison simply does not have enough mass to have any effect on our orbit. If Ison was capable of pulling us out of orbit, the moon, which has a much, much larger mass would have done it years ago! Of course there is more to gravity than mass alone, distance plays a part. The closer you are to an object the greater it's gravitational effect. So what are the distances?

Distance of the sun from earth:                         149,597,870,700 metres                        
Distance of Ison from earth (at closest point):     69,000,000,000 metres
Distance of the moon from earth:                             384,403,000 metres

Ison will get a little over half as close to earth, as earth is to the sun. Although its twice as close to earth as the sun, because it's gravitational pull is so much smaller than the sun, it will have no effect. Now the moon which orbits the earth does have an effect on earths orbit. As you can see the moon is much closer to earth than Ison will ever get, 179 times closer in fact! Not only is the moon 179 times closer but its mass is 23,180,032,138,295 greater than that of Ison!

The moons gravity does have an effect on the earth, it's whats known as "the wobble" which you can see in the image to the left. But as we all know (because we are alive) the moon's gravity is not enough to throw the earth out of orbit.

If you are still not convinced you can work out the gravitational pull of the Sun, Earth, Moon and Ison for yourself, using the figures above and Newtons law of gravity below.

F= gravitational force in newtons (this is the answer)

G = Universal Gravitational Constant = 6.6726 x 10-11N-m2/kg2

m1 =Mass of Object 1 (in kg)

m2 =Mass of Object 2 (in kg)

r = Distance Between the Objects. (in metres)

Ison is going to pull mars out of orbit and throw it in to the earth!

No it wont.

Mars will not be pulled out of orbit for all the same reasons the earth will not be pulled out of orbit. Sure mars has less mass than the earth, and it is farther away from the sun, but it still dwarfs Ison. If you still think mars is going to go AWOL, and want to do the maths to check for yourself, then:

  1. You really need a life, and that's quite a statement from an astronomer!
  2. You need the figures below.
  3. You need Newtons law of gravity which you can find above.

Mass of mars:                        641,719,293,029,551,205,000,000 kg
Mass of Ison (estimated):                                3,175,146,590,000 kg

Distance between mars and the sun:      227,900,000,000 metres
Distance between mars and ison:             10,460,736,000 metres

Ison is a spaceship / UFO!

No it's not.

This is the picture that is circulating the internet as "proof" Ison is a UFO.
To non-astronomers it must look quite stange and we totally get why some might wonder what is going on! Why is there three blobs of light? Why are they in a "V" shape? 
This image comes from the Hubble space telescope and were taken on the 30th of April. The image is not one photograph, but a series of photos stacked on top of each other to make one picture, known as a composite. 
Composite images are quite comon and usuful in astronomy.

The 3 images that make up the composite.

The comet does not look the same in each picture because both the comet and the Hubble telescope are moving. The comet is blurred, just as a picture taken out the window of a moving car will be blurred. For this image the Hubble telescope was pointing at the background stars and galaxies rather than tracking the comet.
Most of the blurring is because Hubble was moving rather than the motion of Ison. Hubble is orbiting the Earth every 95 minutes. The third exposure ended 46 minutes after the start of the first exposure. During that time Hubble moved from one side of the earth to the other, a distance of about 13,000 km (8000 miles). Because the comet is close to us compared to the stars in the background, it looks like its position changes, but it's really Hubble's position that has changed the most! This effect is known as Parallax. Parallax is completely normal when viewing objects inside our solar system. 
Imagine you are at a fairground, you're on the Twister, your mate is watching you. If you take three photos of him and then edit them into one image, you'll have three images of him all at slightly different angles, in different positions compared to the background, because you are moving!

So why the V shape?
Again this is because of Hubble is moving around the earth. If you look at the animation to the left, you can see the path that Hubble takes. The red line is Hubble's orbit AROUND the earth. The white line is Hubble's path through SPACE.
Think of the Twister at fairground again. The ride spins around in one direction, while at the end of the arms, the cars spin in the opposite direction. Well Hubble is doing the same thing!

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