Nasa telescope will hunt for new worlds and try to uncover the secrets of the universe

A new space telescope is preparing to blast off on a mission to uncover some of the universe's biggest secrets, with a UK astronomer helping to lead the hunt for distant worlds.

Nasa's Nancy Grace Roman Space Telescope is scheduled to launch from Florida, USA, on Sunday 30 August at lunchtime UK time.

It will travel aboard a SpaceX Falcon Heavy rocket. Its main mission will last five years, costing about $4.3 billion (£3.2 billion), but it could continue working for longer.

Nasa describes the telescope as having a "powerful wide-eyed view".

Roman has a mirror 2.4 metres wide, the same size as the iconic and famous Hubble Space Telescope's main mirror.

However, the Roman telescope can photograph an area of sky more than 200 times larger in a single view. This means it should monitor huge parts of space much faster than Hubble.

The telescope will observe infrared light, which human eyes cannot see but can reveal objects hidden by clouds of space dust.

Scientists expect Roman to discover more than 100,000 exoplanets, the name given to planets orbiting stars beyond our solar system.

It will search in two main ways. One method watches for the tiny dip in a star's brightness when a planet crosses in front of it.

The other method, called gravitational microlensing, watches what happens when one star passes in front of a more distant star. The gravity of the nearer star bends the distant star's light, making it appear brighter for a short time.

If a planet is also orbiting the nearer star, the planet's gravity can cause an extra change in that brightness too. Scientists use this change to work out if a planet is there or not.

Dr Eamonn Kerins, from Jodrell Bank Centre for Astrophysics at The University of Manchester, leads a group studying planets found using the first method and is part of a team using the second.

He said: "The science we expect Roman to deliver will be simply incredible, transforming our understanding of planets around other stars."

Roman will also investigate two of the universe's biggest mysteries: dark matter and dark energy.

Scientists cannot see dark matter directly because it does not give off or reflect light. However, they know something is there because its gravity affects how stars and galaxies move and bends light travelling through space. Roman will study millions of galaxies to map where this hidden matter may be.

Scientists have also discovered that the universe is expanding, meaning the space between distant galaxies is growing. This expansion appears to be getting faster.

Dark energy is the name scientists use for whatever may be causing this acceleration. Roman will measure the positions and distances of galaxies to investigate how the universe's expansion has changed over billions of years.

Scientists believe about 27% of the universe consists of dark matter and around 70% of dark energy, but still do not know exactly what they are.