objects have oceans of water underneath their icy trusts. you have the conditions that you need for a life. similarly with marius, 3.8 billion years ago, that had the conditions then. you need liquid water, the right chemistry, a source of heat, and you need time for life to develop. that is the recipe for life. i am confident that in the next few missions, we will actually find the possibility of life elsewhere in our own solar system. that takes us on also two planets around other stars. we are looking in ourown around other stars. we are looking in our own solar system. we only know at the port of life on earth, oui’ know at the port of life on earth, our own planet. but we think that could be life elsewhere, and the habitability is there. we are getting at this question, looking at habitability, then take that on two extrasolar planets as well, it is an exciting

time for space and scientific exploration. thank you. back to this morning's explosion on a tube train in london. in the past 30 minutes the prime minister has announced that the terror level is raised to critical, their highest level, that means another attack is imminent. this is what theresa may had to say. i have just been updated on the investigation into this morning's cowardly terrorist attack in london. a major covert and overt investigation is taking place, involving police and security officials. if i said earlier today that the national threat level was being kept under review. thejoint terrorism analysis centre, that is the independent organisation which is responsible for setting the threat level, on the basis of available intelligence, has now decided to raise the threat level from severe to critical. this means that their assessment is that a further attack may be imminent.

following that decision that police have asked for authorisation from the secretary of state for defence to enact part of the first phase of operation tempura, a well established plan to provide military support to the police, and for this period military personnel will replace police officers on guard duties at certain protected sites which are not accessible to the public. the public will see more armed police on the transport network and on our streets, providing extra protection. this is a proportionate and sensible step which will provide extra reassurance and protection while the investigation progresses. the public should go about their business in the normal way and as usual be vigilant and cooperate with the police. i said earlier that terrorism is a great challenge of oui’ terrorism is a great challenge of ourtimes, terrorism is a great challenge of our times, but by standing together we will defeat it. will the public

see anything different in their daily lives now? what they will see isa daily lives now? what they will see is a greater presence of armed police on the transport network and on our streets. this will provide a greater degree of protection, but also the issuance to the public, but the public should go about their business in the normal way but be vigilant and cooperate with the police. that was the prime minister speaking in the last 15 minutes or so, with the terror threat level nobody is from severe to critical. all day we happily from eyewitnesses who were near to that incident this morning, they described what they saw, and indeed the panic that briefly set i was sitting in the back carriage. suddenly i heard a big bang. i turned left and i saw the fireball surged towards me. the fireball came and singed all my here. i have got burn marks on the top of my head.

everybody ran off the train. burn marks on the top of my head. everybody ran off the trainm burn marks on the top of my head. everybody ran off the train. it was quite scary. all the way down the carriage, i was two thirds down, i could see where it happens, smoke rose up, people were running from that carriage and bringing other people down. when we got off we could see remnants of people's bags. they just let could see remnants of people's bags. theyjust let what they could. i walked into the station. people were running down the stairs screaming, crying, running. the entire station was evacuated. people were coming out of the station covered in blood and dirt. we got to the steps and it was their worst, it was like a human crash that we got stuck in. there was a woman underneath me. a little boy, his face had got smacked into the step. i was holding on to the reeling in a fleet of possession, but there was where is of people screaming. it was awful. it was really traumatic. people on board

that train at parsons green this morning. earlier i spoke to the transport police. the underground and the overg round transport police. the underground and the overground is cctv rich, hundreds of officers will be looking at thousands of hours of cctv. they will be piecing together. they will be looking outside of the various stations and on to the streets. it —— there is a superb opportunities in this investigation. there are only a relatively small number of tube stations prior to parsons green on that journey where tube stations prior to parsons green on thatjourney where this particular device could have been brought on from. yes, that is true. but it could have come from network rail, into wimbledon, there are a number of different ways it could have got into the system. but that isa have got into the system. but that is a good chance that there is some good cctv of this character getting onto this chain. the actual tube

train itself is still at the scene now. you would imagine that to be the case for a good while? this is a huge opportunity, with a partially exploded device, the opportunity to get all the forensic recovery from that, to look at all the various ingredients in there, and they are conscious of the fact we have got to do an extremely thorough job before that tube train gets moved, but equally they are aware of the impact it has, the system out of action for a long period of time, but the number one priority, this is a crime scene and will take as long as it ta kes. scene and will take as long as it takes. how much hell can the public offer here? a huge amount of help. people have already taken photographs. there will be filmed from cameras, there will be eyewitnesses themselves to the event. people will come forward with all that information now that the assista nt all that information now that the assistant commissioner has already asked for that to be forwarded to

the police. and there will be intelligence from the community. people will start to put two and two together about other people's behaviours, and this will be a massive and fast—moving investigation, using every piece of material, to track down the offender oi’ material, to track down the offender orfenders. material, to track down the offender or fenders. on that public rule, this happened at the height of the rush hour, it was a busy train, presumably those who are looking to carry out attacks like this will tend to try and do it at its busiest time? the objective obviously is to kill people and gets massive publicity and we have seen that from the dreadful attacks earlier this year and also 7/7 attacks. the sort of precautions we have got to take lie everywhere, not just of precautions we have got to take lie everywhere, notjust on the underground, not just on lie everywhere, notjust on the underground, notjust on the transport system. just a word on the

design of this particular gene, these are comparatively new trains on specific lines on the london underground. if you go on board a train like this and there is no sense of the characters being divided in the way that they were. they clearly are separate carriages but they are joined together. we are going to take you away from that. the assistant commissioner is just approaching the microphone outside new scotland yard now. let us outside new scotland yard now. let us have a listen to what he is saying. i would like to update on the progress of the investigation. we are making excellent progress at the moment as we pursue our lines of inquiry to identify, locate, and to arrest those responsible. this is a very complex investigation which is continuing at speed with the weight of the resources assisted by collea g u es of the resources assisted by colleagues around the country and by oui’ colleagues around the country and by our intelligence agency partners such as mi5. we have hundreds of

police officers trawling through cctv footage, detectives have spoken to many witnesses and we have taken a large number of calls from the members of the public. and members of the public have sent in so far 77 images and videos they have taken at the scene which they have sent into oui’ the scene which they have sent into our appeal website and they are being assessed for evidential value. meanwhile, the improvised explosive device on the train, the remnants of it have now been made safe and that has been taken away for specialist examination by forensic scientists. the last thing i want to see about the investigation is that during the course of the date there has been some uninformed speculation on social media and from journalists, i would like to emphasise that that is not helpful, as we try to pursue this fast—moving investigation. whilst we chased down the suspects, as the public would expect, we are

strengthening our policing resources on the streets of london and indeed across the country, whilst continuing the investigation. the public should expect to see extra police resources, and and and and, on the streets, additional stop and search using counterterrorism powers, and additional road checks on the roads. to do this it makes sense to maximise resources and you will have heard earlier from the prime minister that the threat level has been moved to critical. i have asked government ministers earlier on for permission to use members of the military to free up extra police resources . the military to free up extra police resources. what that gives me and my tea m resources. what that gives me and my team is an extra 1000 armed police officers, who are feedback by being backfilled by soldiers, so i can use those 1000 police officers around the country to provide extra reassurance. what this means for the

public over the weekend is, at transport hubs, at events, in crowded places, they will see these extra resources . crowded places, they will see these extra resources. they will be armed and and arm. they should be reassured that some resources will be acting covert in their protection. finally, iwould be acting covert in their protection. finally, i would say to the public, please remain vigilant as you go about your weekend. if you do see or hear about anything that concerns you please act on your instincts and don't hesitate to call us. what progress are you making in identifying who planted that bomb? we are working to all those lines of inquiry and making good progress on that investigation. i know there is a clamourfor that investigation. i know there is a clamour for more that investigation. i know there is a clamourfor more detail. you will understand when they have got heavy covert components to what we are doing it would be wrong to put information out at this time.

we have to be open—minded. somebody has planted this improvised explosive device on the tube. we had to be open—minded that this stage about him and potential associates. what information hardly got about the background of a suspect i suspects? it is routine in these circumstances that is will claim responsibility. how sophisticated was the device? i had a detailed briefing on the device, its components, how it works, to put that information out publicly at the moment would not be appropriate. we are only aware of one device. we now have the remnants of that device, it will be examined by our experts, we

will be examined by our experts, we will chase down suspects, and i repeat, firstly, members of the public should be reassured by the extra officers they will see on the streets over the weekend in london and elsewhere, and again, any information on anything, please do not hesitate to act on your suspicion and call the police. do you believe there may be other devices? their words of the assistant commissioner, mark rowley, outside new scotland yard, with the update their on the investigation into today's events in parsons green. he is talking about excellent progress having been made, and reference of course true that terror warning, severe to critical, and the light of what the prime minister severe to critical, and the light of what the prime minister has severe to critical, and the light of what the prime minister has set severe to critical, and the light of what the prime minister has set in the last few moments. here is the weather. it has turned to add sherry over the last few days and that is how we begin the end. quite a few showers but that will slowly ease,

particularly by sunday there will be sunny spells as well and some chilly nights. there could be a touch of frost. it will be fairly chilly tonight. some showers tonight. east coasts, pa rt of tonight. some showers tonight. east coasts, part of wheels, clear spells elsewhere. in the countryside it will be cooler than that. tomorrow morning we will start off with showers across north—east scotland's, north—east england, other areas starting the day fine and dry with spells of sunshine. cloud will bubble up. some showers will be heavy and thundery particularly towards the south—east. as we get on into sunday we will see fewer showers, more in the ray of sunshine, and after a chilly start to the day, temperatures of 18 degrees. this is bbc world news today.

i'm lukwesa burak. our top stories: the terror threat level in the uk is raised to ‘critical‘ after an explosion hits a morning rush—hour commuter train in london. thejoint terrorism the joint terrorism analysis centre, the independent organisation responsible for setting the threat level on the basis of available intelligence, has now decided to raise the national threat level from severe too critical. it's the fifth terror attack in the uk this year. the so—called islamic state group says that what it called one of its "detachments" planted the device. the un meets to discuss north korea's latest missile launch, after the united states calls on beijing to take direct action. cassini ends its 20—year mission by heading directly for saturn before burning—up in the planet's atmosphere.