They rejoice under a wide variety of names - enablers, front-of-house facilitators, informal learning communicators - but they all share a mission to explain.
They are the army of enthusiastic volunteers and knowledgeable amateurs, resting entertainers and genuine scientists promoting a new age of enlightenment in museums and science centres.
Explainers are playing an increasingly important frontline role as visitors flock to find out more about science in general and today's specific talking points, such as climate change and creationism, often asking some very big questions along the way.
But they haven't always been in such huge demand or held in such high esteem. Anthony Richards joined the staff at the Science Museum as an explainer nearly 20 years ago and remembers his ilk being treated as "the lowest of the low".
"They were gallery assistants standing around for health and safety reasons, to be honest," he says. "They weren't considered an aid to learning, they received no training and turnover was rapid. So we took a look at the job and decided that we needed knowledgeable people who worked well with children."
And that was a problem in itself, one which still resonates throughout the sector: how to find a scientist with sufficient social skills to communicate clearly to non-experts.
"The joke goes: 'How do you recognise an extrovert mathematician?'" asks Richards. "He stares at your shoes while talking to you. There are very few people good at both disciplines."
Stage presence
So the museum looked for people from an entertainment background, advertising in performing arts newspaper the Stage for out-of-work actors to apply for a leading role with a difference.
"That was difficult, too, as they were always looking for acting jobs," Richards says. "The museum came a very poor second and they disappeared completely for the panto season. And some of them couldn't cope without hiding behind a character."
Former primary schoolteachers were also tried and tested, but they simply brought a rigid classroom aesthetic to a museum keen on establishing a very informal learning environment.
Eventually, a cast of theatre graduates with a keen interest in museums was hired and a great deal of time and money was spent on training them.
"When I first started, they would interview people by asking them to wire a plug and talk about a mystery object - usually a mercury tilt switch. That approach is totally irrelevant; it's far more useful to be able to tell the difference between a nine-year-old and a 12-year-old child," says Richards.
Applicants are now asked to prepare presentations from boxes of props and toys to ensure they have the required charisma and storytelling ability.
"Amateur psychologists"
Richards uses his own experiences in his role as gallery programmes manager, overseeing the current crop of 70 explainers.
"A lot of people disagree with how we look for potential explainers as they think an armful of degrees is far more important, but this isn't a university. We're interested in people who build a rapport with visitors and who can overcome barriers to learning. We want proactive explainers who can see when visitors are lost or struggling and know how to help."
That gut instinct also kicks in on the gallery floors at Birmingham science centre Thinktank, where enablers often act as "amateur psychologists", according to informal learning manager Kenny Webster.
"A lot of what we do is human nature, reading visitors' body language, making eye contact or reacting to overheard snippets of conversation. We encourage people to think for themselves by pointing out why aspects of science can be important in their lives.
"There are people, for example, who don't believe in evolution for one reason or another. Our approach is purely scientific and if people don't want to accept the science, that's up to them, as long as they have thought about it.
"But coming to the wrong conclusion about MMR jabs based on something they've heard in the pub could have serious consequences. Those are the sort of things we try to tackle," states Webster, who says many of Thinktank's enablers were hired for their communication skills, and only learned to love the science along the way.
The Thinktank enablers, easy to spot in vivid yellow shirts, also look after school groups during term time and engage with families at weekends and during holidays. They take part in storytelling sessions, workshops and science sideshows and make sure everything in the museum is switched on and working.
Thinktank also recruits from the local community, one of the most deprived areas of the country. Borrowing a career scheme from the New York Hall of Science, it provides young people with an introduction to museums as well as the skills and confidence that could lead to job in science.
From eight to 80
At the Natural History Museum (NHM) there are three different teams of people - each with their own qualifications, training requirements and learning contexts - who make sure visitors are not blinded by science.
The 26 science educators, all armed with science degrees and previous experience in communicating with the public, carry out behind-the-scenes curatorial duties, lead tours of the exhibits and organise science shows and practical sessions. There are also 130 learning volunteers who share a passion for natural history and the gift of stimulating conversation. The final team is the communicators.
"We take the trouble to find out why they want to give us their time," says Honor Gay, the NHM's head of learning, "and we do our best to equip them to assist people or, indeed, to move into a museum career. We don't have them simply to save money."
Volunteers are aged from 80 down to eight; there are currently 10 youngsters kitted out in official uniforms and trained to help talk to other kids during the holidays.
The older ones roam the galleries engaging visitors, says Gay, "with charismatic specimens such as sabre-toothed tiger skulls. It's all about constructive learning and generating high-quality questions from the visitor."
To cater for every eventuality, volunteers are trained in everything from the history of the museum to evacuation procedures, behaviour management to the national curriculum.
The final team is the communicators who moderate the daily Nature Live sessions in which the most confident of the museum's 350 scientists talk about their work.
"In the past, visitors, collections and scientists were isolated from each other. The communicators are bridging that gap," adds Gay.
The best explainers/facilitators/communicators should provide excitement and inspiration to increase the scientific literacy of visitors, says Penny Fidler, director of the Association for Science and Discovery Centres (formerly Ecsite-uk).
"We should all be striving towards shared ownership of science where people are confident in giving their opinion or wanting to find out more if they object to something," says Fidler. "Twenty years ago, we didn't have the number of ethical debates we have now. Issues such as stem cell research aren't really up to scientists to decide. It's up to the public and we need people able to engage in those debates."
Out of this world
Choosing who does the explaining at the National Space Centre (NSC) in Leicester - where, for once, most things actually are rocket science - depends on the type of audience, which can include anyone from small children to inveterate cosmic anoraks.
As well as an in-house space communications team (all experts in the field, confident in front of people), an education group manages workshops and presentations as well as transporting the venue's inflatable planetarium around schools in search of the astronomers of the future. The centre also calls on the services of external experts from academia or industry to talk through the fine detail of the UK's often-overlooked and under-appreciated role in the space industry.
"Complementing the scientists, we have people from entertainment backgrounds bec-ause even though this is an educational facility, it's all about getting the message across in an engaging way," says Malika Andress, the head of marketing at the NSC.
"For example, we worked closely with EADS Astrium [a European aerospace firm] on a session explaining how a UK-built robot is going to Mars in 2016. They brought one into our test centre and the kids loved it.
"Because the UK doesn't participate financially in human space flight, it's up to us to inform people who think astronauts are the be-all-and-end-all that we actually lead the world in satellite technology and robotics," Andress adds.
Frequently asked questions vary from the perennial "going-to-the-loo-in-space" enquiries through to the cost of space tourism and the whispers that the moon landings might have been staged in the Nevada desert.
"We enter that debate; we have lots of Nasa documentation and moon rock that came back in 1972," says Andress. "We ask them why they disbelieve in something of this nature. Just standing there and saying 'you are wrong' is not the right attitude.
"It's about informed debate. Some of the subject matter can be a bit geeky, but the story of space can be inspirational. Ninety per cent of the children who visit us say they'd rather be astronauts than footballers."
John Holt is a freelance journalist
They are the army of enthusiastic volunteers and knowledgeable amateurs, resting entertainers and genuine scientists promoting a new age of enlightenment in museums and science centres.
Explainers are playing an increasingly important frontline role as visitors flock to find out more about science in general and today's specific talking points, such as climate change and creationism, often asking some very big questions along the way.
But they haven't always been in such huge demand or held in such high esteem. Anthony Richards joined the staff at the Science Museum as an explainer nearly 20 years ago and remembers his ilk being treated as "the lowest of the low".
"They were gallery assistants standing around for health and safety reasons, to be honest," he says. "They weren't considered an aid to learning, they received no training and turnover was rapid. So we took a look at the job and decided that we needed knowledgeable people who worked well with children."
And that was a problem in itself, one which still resonates throughout the sector: how to find a scientist with sufficient social skills to communicate clearly to non-experts.
"The joke goes: 'How do you recognise an extrovert mathematician?'" asks Richards. "He stares at your shoes while talking to you. There are very few people good at both disciplines."
Stage presence
So the museum looked for people from an entertainment background, advertising in performing arts newspaper the Stage for out-of-work actors to apply for a leading role with a difference.
"That was difficult, too, as they were always looking for acting jobs," Richards says. "The museum came a very poor second and they disappeared completely for the panto season. And some of them couldn't cope without hiding behind a character."
Former primary schoolteachers were also tried and tested, but they simply brought a rigid classroom aesthetic to a museum keen on establishing a very informal learning environment.
Eventually, a cast of theatre graduates with a keen interest in museums was hired and a great deal of time and money was spent on training them.
"When I first started, they would interview people by asking them to wire a plug and talk about a mystery object - usually a mercury tilt switch. That approach is totally irrelevant; it's far more useful to be able to tell the difference between a nine-year-old and a 12-year-old child," says Richards.
Applicants are now asked to prepare presentations from boxes of props and toys to ensure they have the required charisma and storytelling ability.
"Amateur psychologists"
Richards uses his own experiences in his role as gallery programmes manager, overseeing the current crop of 70 explainers.
"A lot of people disagree with how we look for potential explainers as they think an armful of degrees is far more important, but this isn't a university. We're interested in people who build a rapport with visitors and who can overcome barriers to learning. We want proactive explainers who can see when visitors are lost or struggling and know how to help."
That gut instinct also kicks in on the gallery floors at Birmingham science centre Thinktank, where enablers often act as "amateur psychologists", according to informal learning manager Kenny Webster.
"A lot of what we do is human nature, reading visitors' body language, making eye contact or reacting to overheard snippets of conversation. We encourage people to think for themselves by pointing out why aspects of science can be important in their lives.
"There are people, for example, who don't believe in evolution for one reason or another. Our approach is purely scientific and if people don't want to accept the science, that's up to them, as long as they have thought about it.
"But coming to the wrong conclusion about MMR jabs based on something they've heard in the pub could have serious consequences. Those are the sort of things we try to tackle," states Webster, who says many of Thinktank's enablers were hired for their communication skills, and only learned to love the science along the way.
The Thinktank enablers, easy to spot in vivid yellow shirts, also look after school groups during term time and engage with families at weekends and during holidays. They take part in storytelling sessions, workshops and science sideshows and make sure everything in the museum is switched on and working.
Thinktank also recruits from the local community, one of the most deprived areas of the country. Borrowing a career scheme from the New York Hall of Science, it provides young people with an introduction to museums as well as the skills and confidence that could lead to job in science.
From eight to 80
At the Natural History Museum (NHM) there are three different teams of people - each with their own qualifications, training requirements and learning contexts - who make sure visitors are not blinded by science.
The 26 science educators, all armed with science degrees and previous experience in communicating with the public, carry out behind-the-scenes curatorial duties, lead tours of the exhibits and organise science shows and practical sessions. There are also 130 learning volunteers who share a passion for natural history and the gift of stimulating conversation. The final team is the communicators.
"We take the trouble to find out why they want to give us their time," says Honor Gay, the NHM's head of learning, "and we do our best to equip them to assist people or, indeed, to move into a museum career. We don't have them simply to save money."
Volunteers are aged from 80 down to eight; there are currently 10 youngsters kitted out in official uniforms and trained to help talk to other kids during the holidays.
The older ones roam the galleries engaging visitors, says Gay, "with charismatic specimens such as sabre-toothed tiger skulls. It's all about constructive learning and generating high-quality questions from the visitor."
To cater for every eventuality, volunteers are trained in everything from the history of the museum to evacuation procedures, behaviour management to the national curriculum.
The final team is the communicators who moderate the daily Nature Live sessions in which the most confident of the museum's 350 scientists talk about their work.
"In the past, visitors, collections and scientists were isolated from each other. The communicators are bridging that gap," adds Gay.
The best explainers/facilitators/communicators should provide excitement and inspiration to increase the scientific literacy of visitors, says Penny Fidler, director of the Association for Science and Discovery Centres (formerly Ecsite-uk).
"We should all be striving towards shared ownership of science where people are confident in giving their opinion or wanting to find out more if they object to something," says Fidler. "Twenty years ago, we didn't have the number of ethical debates we have now. Issues such as stem cell research aren't really up to scientists to decide. It's up to the public and we need people able to engage in those debates."
Out of this world
Choosing who does the explaining at the National Space Centre (NSC) in Leicester - where, for once, most things actually are rocket science - depends on the type of audience, which can include anyone from small children to inveterate cosmic anoraks.
As well as an in-house space communications team (all experts in the field, confident in front of people), an education group manages workshops and presentations as well as transporting the venue's inflatable planetarium around schools in search of the astronomers of the future. The centre also calls on the services of external experts from academia or industry to talk through the fine detail of the UK's often-overlooked and under-appreciated role in the space industry.
"Complementing the scientists, we have people from entertainment backgrounds bec-ause even though this is an educational facility, it's all about getting the message across in an engaging way," says Malika Andress, the head of marketing at the NSC.
"For example, we worked closely with EADS Astrium [a European aerospace firm] on a session explaining how a UK-built robot is going to Mars in 2016. They brought one into our test centre and the kids loved it.
"Because the UK doesn't participate financially in human space flight, it's up to us to inform people who think astronauts are the be-all-and-end-all that we actually lead the world in satellite technology and robotics," Andress adds.
Frequently asked questions vary from the perennial "going-to-the-loo-in-space" enquiries through to the cost of space tourism and the whispers that the moon landings might have been staged in the Nevada desert.
"We enter that debate; we have lots of Nasa documentation and moon rock that came back in 1972," says Andress. "We ask them why they disbelieve in something of this nature. Just standing there and saying 'you are wrong' is not the right attitude.
"It's about informed debate. Some of the subject matter can be a bit geeky, but the story of space can be inspirational. Ninety per cent of the children who visit us say they'd rather be astronauts than footballers."
John Holt is a freelance journalist
What the explainers say…
Shan Ali Abid is 17 years old and has been working at Thinktank as a junior enabler for more than six months.
"The career ladder scheme gives students from the local community an enormous opportunity to gain experience at such a young age. We take various responsibilities, learn and teach about science and heritage and generally offer good customer service to the visitors. I have certainly started to enjoy science more than I ever thought I would. Before I left school I had no idea of what the future might hold. Now, I would dearly love to get a degree in science."
Shayna Barby is a learning volunteer at the Natural History Museum and is studying for a BSc in environmental conservation.
"The induction training was excellent and covered everything from specimen background and learning styles to radio communications and health and safety. The volunteer role stays fresh because each visitor interaction is unique. I always enter the museum excited and come away fulfilled. I enjoy helping children to unravel the mystery of the tarantula mount on the Creepy Crawlies focus point."
Shan Ali Abid is 17 years old and has been working at Thinktank as a junior enabler for more than six months.
"The career ladder scheme gives students from the local community an enormous opportunity to gain experience at such a young age. We take various responsibilities, learn and teach about science and heritage and generally offer good customer service to the visitors. I have certainly started to enjoy science more than I ever thought I would. Before I left school I had no idea of what the future might hold. Now, I would dearly love to get a degree in science."
Shayna Barby is a learning volunteer at the Natural History Museum and is studying for a BSc in environmental conservation.
"The induction training was excellent and covered everything from specimen background and learning styles to radio communications and health and safety. The volunteer role stays fresh because each visitor interaction is unique. I always enter the museum excited and come away fulfilled. I enjoy helping children to unravel the mystery of the tarantula mount on the Creepy Crawlies focus point."