ESA's SOHO Spacecraft image of Ison

With the US shutdown there has been a lack of images coming from NASA, which is particularly disappointing as last week Ison made her closest pass to Mars. Luckily the European Space Agency (ESA) is still up and running and releasing images! The ESA's Solar and Heliospheric Observatory or SOHO for short is a satellite that was launched in 1995 to study the Sun with a variety of on board instruments.Originally the SOHO mission was only going to last a couple of years but due to the amazing results it was producing it is still running today.

The SOHO craft is fitted with a special instrument called SWAN (Solar Wind ANisotrpies) which is the only instrument on board not to be pointed at the Sun, instead it looks at everything else! Swan watches the rest of the sky, measuring hydrogen that is ‘blowing’ into the Solar System from interstellar space. 

By studying the interaction between the solar wind and this hydrogen gas, SWAN determines how the solar wind is distributed. The ESA have used SWAN to detect the hydrogen in Ison's coma, which should be able to tell us how much water is being produced and at what rate. The data from SWAN should give us great new insights in to the emissions given off by sun grazing comets like Ison.

Ison captured by European Space Agency's SOHO craft using the SWAN instrument

The image above is the first image of Ison taken by SWAN to be released by the ESA, over the next few weeks as Ison brightens we should get ever more impressive pictures. Swan takes 360 degree images of space the only thing it doesn't picture is the Sun and the Earth, which are the dark spots on the image. What SWAN is photographing is the effect that solar wind has on the element hydrogen. Sounds complicated but its quite simple really, imagine you wanted to take a picture of the wind, but you cant see it. So you photograph the effect the wind has blowing dust on the ground or on the leaves of a tree, this is basically what SWAN does! Instead of dust and leaves it photographs the effect on hydrogen by the solar wind. What makes this camera particularly important for studying Ison is that because it basically photographs hydrogen, we can tell how much hydrogen is being given off by Ison, which is the main make up of a comets coma and tail. Now even we will admit that this image is not the most spectacular of Ison we've seen, but as Ison gets closer to the sun and more hydrogen is given off  her coma and tail will expand and the images by SWAN will get bigger and better and the data will be invaluable! 

Ison update 30/09/2013

These are the current co-ordinates for Ison at 18.45 GMT  30/09/2013

Co-ordinates: 09h 34m 06.4s,   17* 40'  08.9"
Distance from Sun: 247,607,969 km
Distance from Earth: 322,707,837 km
Magnitude: 11.12

For those who don't know you can track Ison in real time from the comfort of your computer by visiting the fantastic The Sky live website

With thanks to The Sky Live

NASA Prepares for Ison's flyby of Mars

Tomorrow see's Ison reach it's closest approach to Mars. Ison is going to come within just 10,460,730 km of Mars, six times closer than it will get to Earth!

There are currently 5 active Mars missions which will be turning their attention towards Ison, 2 rovers and 3 orbiters. The best equipped to study Ison are NASA's Mars Reconnaissance Orbiter (MRO) and ESA's Mars Express Orbiter (MEO).

Artists impression of Ison from the surface ofMars

Mars Reconnaissance is equipped with the largest telescope ever taken in to deep space at 20 inches, however it was designed with surface observation, rather than imaging comets! Like wise Mars Express original purpose is also terrestrial mapping and comes equipped with the very impressive HRSC Camera. Between them MRO and MEO should give us some stunning pictures and the most in depth data on Ison so far.  We are hoping to get much more accurate data on her size, the larger she is the more likely she will survive her encounter with the Sun at the end of November.
What's more as she passes Mars she is warming up more causing her tail to grow and increasing her coma. With all these orbiters and rovers pointed in her direction, we should get a fascinating glimpse in to how chunks of ice evolve and grow into the magnificent comets we all know!

Mars Reconnaissance Orbiter

All of this is just a small part of the research being conducted on Ison. A grand total of 16 NASA craft will be observing Ison from space along with the Hubble space telescope, 4 ESA spacecraft and every observatory on Earth! Ison is without doubt the most study comet there has ever been, and we are extremely excited to find out what secrets will be unlocked!

A Newbies guide to Ison part 4

What is Perihelion?

Perihelion is term we use to mean that a comet has reached its closest point to the sun. Comet Ison's perihelion is on the 28th of November at approximately 23:00 GMT when she will pass the Sun at a distance of around 1,200,000 Km (800,000 miles)

What is A.U?

A.U is a measurement of distance, and stands for Astronomical Unit.
A.U is the distance between the Earth and the Sun which is 149,597,870,700 km (92,955,807,273 miles). So if you see Ison's distance from earth as 2.0 A.U this means it is twice as far away as the Earth is from the Sun. 

Mars Express to start imaging Ison today

The European Space Agency will give it’s Mars Express Orbiter craft a new mission tonight, to start photographing Ison. Mars Express will get some of the best views in the solar system as Ison will pass Mars at just 10.5 million kilometres, three times closer than it will get to Earth. 

Mars Express is hoped to produce the some of the best data on the composition of Ison’s corona that we will get, so we are egarly awaiting the results. Mars Express is well equipped and with such an impressive aray of instruments at the ESA disposal, we are expecting some great insights in to Isons life.

The Mars Express Orbiter will start observing Ison today 24/09/2013

 Surface/subsurface instruments
· HRSC (High Resolution Stereo Camera)
· OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer)
· MARSIS (Sub-surface Sounding Radar Altimeter)
 Atmosphere/Ionosphere instruments
· PFS (Planetary Fourier Spectrometer)
· SPICAM (Ultraviolet and Infrared Atmospheric Spectrometer)
· ASPERA (Energetic Neutral Atoms Analyser)
  

 This is just the start of a four pronged mission from the European Space Agency to study Ison. In November the ESA/NASA SOHO mission will turn its sights on Ison, then it’s the turn of the Venus Express orbiter and the Proba-2 satellite. We will bring you more information on these missions closer the time!

A newbies guide to Ison part 3

How fast is Ison?

Ison is moving fast! As of September she is traveling at approximately 107826 kph (67,000 mph), at this speed it would take Ison just 10 seconds to travel the entire length of the M1 motorway! 

But that's not the whole story, Ison is accelerating. As the comet gets closer to the sun, the effect of the suns gravity is stronger and will cause Ison to speed up. In December when Ison reaches the sun, the sun will "slingshot" her back out into the solar system at tremendous speed. Remember when you were a kid running up to a lamp post, grabbing hold of it and being swung round? Remember how you suddenly speed up, well swap the lamppost for the sun and you for Ison! (If you don't remember doing it, go and have a go now!)

When Ison goes through this slingshot around the sun we expect her to reach speeds of up to 1,359,895 kph (845,000 mph)! At this speed the M1 would take just 0.8 seconds, it is rumoured that Jeremy Clarkson has been seen building a giant harpoon to try and capture Ison.......

Where did Ison come from?

We believe Ison came from the Oort cloud. Our solar system sits inside a large ball shaped cloud of ice and rocks. This is the Oort cloud and is generally considered to be the boundary of the solar system and the birth place of most comets. 

You may notice on the picture above that the cloud has two parts, the inner cloud and the outer cloud. Imagine a football with a dinner plate inside. The outer cloud is where we think Ison came from. The Oort cloud contains trillions of frozen objects, mainly water, ammonia and methane.

The edge of the Oort cloud is about one light year away from the sun, around 22,5000,000,000,000 km (13,950,000,000,000 miles) and at this distance the effect of the suns gravity is very weak. It’s thought that the gravitational effect from our neighbouring stars dislodge chunks of ice and push them in to our solar system where they become comets, like Ison. Very little is known about the Oort cloud in fact most of it is theory, we have yet to send a space probe there! 

What is Ison's mass?

Just like size, it's not easy to work out the mass of comets! Many astronomers are reluctant to even take a guess, but we will! We have estimated Ison to be 3,175,146,590 kg. This estimate was reached by a mean average of estimates from 11 BCRS members. All the estimates were within a 9% range, so we are quietly confident with its accuracy. That said, new data is coming in daily so we might revise this figure in the future, but we would be surprised if it was by much! 

How close to earth will Ison get?

At its closest point Ison will be 69,000,000 km (39,900,000 miles) from earth on the 26th of December.