Beryllium ( /bəˈrɪliəm/ bə-RIL-ee-əm) is the chemical element with the symbol Be and atomic number 4. Because any beryllium synthesized in stars is short-lived, it is a relatively rare element in both the universe and in the crust of the Earth. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl (aquamarine, emerald) and chrysoberyl. As a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal.

Beryllium increases hardness and resistance to corrosion when alloyed to aluminium, cobalt, copper (notably beryllium copper), iron and nickel. In structural applications, high flexural rigidity, thermal stability, thermal conductivity and low density (1.85 times that of water) make beryllium a quality aerospace material for high-speed aircraft, missiles, space vehicles and communication satellites. Because of its low density and atomic mass, beryllium is relatively transparent to X-rays and other forms of ionizing radiation; therefore, it is the most common window material for X-ray equipment and in particle physics experiments. The high thermal conductivities of beryllium and beryllium oxide have led to their use in heat transport and heat sinking applications.

Harald Lesch (born 28. July 1960 in Gießen, Hesse) is a German physicist, astronomer, natural philosopher, author, television presenter, professor of physics at the Ludwig Maximilian University of Munich (LMU) and professor of natural philosophy at the Munich University of Philosophy.

After completing secondary school in 1978 at the Theo-Koch-Schule in Grünberg, Hesse, Lesch studied physics at the University of Giessen, then at the University of Bonn, where he completed his doctoral degree in 1987 and worked at the Max-Planck-Institute for Radio Astronomy. From 1988 to 1991 he was a research assistant at the state observatory at Heidelberg-Königstuhl. In 1992 he was a visiting professor at the University of Toronto. In 1994 he was habilitated at the University of Bonn.

Since 1995 Lesch has been a professor of theoretical astrophysics at the Institute for Astronomy and Astrophysics at the LMU Munich. Additionally, he teaches natural philosophy at the University for Philosophy in Munich. His main areas of research are cosmic plasma physics, black holes, and neutron stars. He is the expert on astrophysics in the Deutsche Forschungsgemeinschaft (DFG) (German Research Society) and a member of the Astronomische Gesellschaft (Astronomical Society). He is also a textbook author.

Liz Bonnin (born 16 September 1975) is a French-born television presenter who has worked on television in the Republic of Ireland and the United Kingdom. She currently works for the BBC.

Bonnin was born in France to a French father who is a dentist and Trinidadian mother.^{[citation needed]} One of her grandfathers is from India.^{[citation needed]} The family moved to Ireland when she was 10 years old.^{[citation needed]} She has a bachelor's degree in biochemistry from Trinity College, Dublin and also holds a master's in Wild Animal Biology from the Zoological Society of London and the Royal Veterinary College (2008), for which she tracked tigers in Nepal. She continues to work on big cat conservation programmes at the Zoological Society.

Bonnin started her career presenting on RTÉ Television in Ireland, on The Den, Telly Bingo, Millennium Eve: Celebrate 2000 and for two years, Off the Rails. In 2002 she moved to London to present on a number of TV channels. She was also part of an Irish girl pop group named Chill, signed to Polydor but they broke up before recording