Herschel operating at the second Lagrange point (L2)

Herschel is set to revolutionise our understanding of the Universe. A versatile infrared space telescope, Herschel's main objective is to study relatively cool objects across the Universe: in particular the formation and evolution of stars and galaxies, and the relationship between the two.

Within our Galaxy, the mission’s main science objectives are:

• To study Solar System objects such as asteroids, Kuiper belt objects, and comets.
  Comets are the best-preserved fossils of the early Solar System, and hold clues to the raw ingredients that formed the planets, including Earth.

• To study the process of star and planet formation.
  Herschel is unique in its coverage of a wide range of infrared wavelengths, with which it is looking into star-forming regions in our Galaxy, to reveal for the first time different stages of early star formation and the youngest stars. The telescope is also studying circumstellar material around young stars, where astronomers believe that planets are being formed, and debris discs around more mature stars.

• To study the vast reservoirs of dust and gas in our Galaxy and in other nearby galaxies.
  Herschel is studying in detail the physics and kinematics at work in giant clouds of gas and dust that give rise to new stars and associated planetary bodies. Herschel is also well suited to studying astrochemistry providing fundamental new insights into the complex chemistry of these molecular clouds, the wombs of future stars.

Outside our Galaxy, the mission’s main science objectives are:

• To explore the influence the galactic environment has on interstellar medium physics and star formation. Most of what we have learned about the physics and chemistry of the interstellar medium, and about the processes there such as star formation has been gained by studies in our own Galaxy. With Herschel, we can carry out similar studies in relatively nearby galaxies as well. For example, studies of nearby low-metallicity galaxies can open the door to the understanding of these processes in the early Universe.

• To chart the rate of star formation over cosmic time. We know that star and galaxy formation commenced relatively early after the Big Bang. We also know that when the Universe was about half its current age, star formation was much more intense than it is today. Herschel is ideal for studying infrared-dominated galaxies at the peak of star formation.

• To resolve the infrared cosmic background and characterise the sources. About half the energy produced and emitted throughout cosmic history now appears as a diffuse infrared cosmic background. With its large telescope, Herschel is resolving the far-infrared background and characterising its constituent sources to a level of detail never achieved before.