The Natural History Museum in London is a beautiful building designed by Victorian architect Alfred Waterhouse. It opened in 1881 in South Kensington, and since 1986 it's also incorporated the former Geological Museum.

I'd like to take you on a special tour of the museum – an astronomy tour. It won't take long by the clock, even though the story takes 13.8 billion years if we start . . .

. . . From the Beginning. It all begins with a Big Bang. Nearly nine billion years pass before the Solar System is born. (I notice that Pluto is still a planet in this gallery.) But the focus is on Earth. We see its physical and chemical evolution, followed by the evolution of life. Finally, visitors are asked to consider possible futures for our home planet.

The Earth Hall is the centerpiece of the Earth Sciences galleries that opened in 1996. An imposing escalator ferries visitors to the upper floors past constellations and through a giant sculpture of the Earth (photo by Jonathan Brennan). But if you follow me through the darkened hall, we'll see something special. In one of the illuminated cases there is a piece of Moon rock that Apollo 16 astronauts brought to Earth in 1972.

Let's keep walking to the older part of the museum. That's where we'll find the rocky part of astronomy, i.e., meteorites. The Natural History Museum has nearly two thousand of them, though only a few are on display. First, we must find the gallery that will take us back to the nineteenth century.

The Minerals gallery shows off the original architecture and design of the museum. It even has wooden display cases housing a fascinating collection of rocks and minerals. And on the back wall we'll find the meteorite display which tells us what they are, how they're classified and why they're important.

If you're not sure what is meant by a meteorite, the answer is that it's a piece of space rock that's fallen to Earth. When the rock was whizzing through the atmosphere, it was a meteor, and when it was still in space, it was a meteoroid.

We might consider meteorites as handy sample return missions, which didn't need spacecraft to go and get them. Scientists can tell a lot about where they came from and the conditions in which they formed. The main disadvantage is not knowing exactly where they came from.

The display contains examples of meteorites and photographs of impact craters. The craters are uncommon on Earth because the surface is constantly renewed by surface weathering, and Earth's interior processes, such as earth movements and volcanoes.

As this photo by J. Gregory Wilson shows, there used to be a small gallery dedicated to meteorites just beyond this exhibit, but that was replaced in 2007.

The Vault is where the Meteorites gallery once was. The museum's Alan Hart describes the exhibits now in The Vault as “rare, scientifically unique and culturally historical”. They include rare meteorites from the Moon and Mars, and space diamonds, including the “oldest thing you'll ever see”.

Most meteorites come from the asteroid belt, but some have been identified as originating on the Moon or Mars. Lunar rocks brought to Earth by Apollo astronauts and Luna robotic missions serve as references for suspected lunar meteorites. The chemical and mineral composition, textures etc. of these meteorites is very similar to the lunar samples, but doesn't fit the profile of Earth rocks or those from the asteroid belt.

We don't have any reference samples of Martian rocks yet. However the shock of the impacts that ejected the rocks into space caused small patches to melt and form little glassy bits. As this occurred, tiny pockets of gas were trapped. Scientists can match the composition of this gas with what we know about the Martian atmosphere, which, like other atmospheres, has its own unique profile.

The Tissint meteorite fell in Morocco in 2011. It's of great scientific interest because it shows unique evidence of weathering caused by water. The meteorite is displayed in a special container to minimize contamination. A large impact some 700,000 years ago knocked this rock off Mars and into space.

A lunar meteorite was found in the Dar Al Gani meteorite field in Libyan Sahara in 1998. It was also ejected from the Moon by the impact of a large asteroid, and eventually captured by the Earth's gravitational field.

The Vigarano meteorite is a piece of a primitive asteroid. Primitive asteroids are made of materials from the solar nebula from which the Solar System formed, and they haven't been changed by heating. The Vigarano meteorite contains material so old that it helped to establish the age of the Solar System.

But there's something on display that's older than that. I don't know if diamonds really are forever, as James Bond would have it, but there are “diamonds from stardust” in a meteorite whose display proclaims it to be the oldest thing we'll ever see.

Don't get too excited by a meteorite full of diamonds. This isn't bling. These diamonds are microscopic. Sometimes tiny diamonds form in a meteorite in response to the shock pressure of a collision. However these diamonds were already in the nebula from which the Solar System formed. This rock is part of an asteroid that incorporated some of this earlier material. The diamonds probably formed when a star exploded as a supernova long before our Sun was born.