Asked by James (aged eight)

At 43 foot (13 metres) long and weighing up to nine tons (heavier than one and a half African elephants), Tyrannosaurus Rex was one of the largest meat-eating dinosaurs to have lived, but not the biggest dinosaur ever. Spinosaurus aegyptiacus was even longer at up to 59 feet (18 metres), and possibly twice as heavy. However, the largest dinosaurs were herbivores, not meat-eaters.

The largest dinosaur we know about from good fossils was the long-necked sauropod Argentinosaurus huinculensis, which was possibly 98 feet (30 metres) long (longer than three London buses end-to-end) and weighed over 90 tons (almost as much as 17 African elephants). Another sauropod dinosaur called Amphicoelias altus may have been larger, but the fossil bones of this creature are lost. Working out the size of dinosaurs is very difficult, because we very rarely find complete skeletons. Normally we only have a few bones available to estimate overall size and weight, so there may be many different estimates.

Dr Stig Walsh, Senior Curator of Vertebrate Palaeobiology, National Museums Scotland

Da Vinci

The first reference to a rotor system is credited to inventor Leonardo da Vinci, who designed an ‘aerial screw’ in 1480. No full-scale variant was constructed during his lifetime.

Steamed

The word ‘helicopter’ was coined by French inventor Gustave de Ponton d’Amécourt, who used it to name his small, steam-powered rotorcraft.

Untethered

The first helicopter to achieve completely untethered flight was the Cornu in 1907, which managed to hover one foot above the ground for 20 seconds.

Fastest

The record for the fastest helicopter in the world is held by the Sikorsky X2 which, during a flyby over Florida, United States, clocked 258mph (416kph).

Phileas

The current world record speed for an eastbound round-the-world helicopter trip is 85 mph (137 kph). The record was set by Edward Kasprowicz in an Augusta A109S Grand.

Asked by Ian Sanders

There has been a series of ice ages over the past million years or so. Sometimes this whole period is referred to as the ‘ice age’, although it has included many individual glacial periods that alternated, every hundred thousand years or so, with warm periods called interglacials. More accurately, the ‘last ice age’ refers to the most recent of these glacial episodes. This global descent into cold climate started about 100,000 years ago and ended 11,700 years ago. That whole period can be regarded as the last ice age, though it was also complex, with varying climate.

The coldest part, when massive glaciers extended as far south as Britain, happened between 25,000 and 20,000 years ago; we call it the last glacial maximum. When will the next ice age be? Past interglacials have been quite variable in length; ours so far has lasted 11,700 years. According to geophysicists, our interglacial still has several thousand years left to run, after which another ice age may well begin. However, human influence could change everything. The climate system is very complex and delicate, and global warming could hugely affect the onset of the next ice age.

Adrian Lister, Palaeontology, NHM London

First in time

The Egyptians were the first culture to become interested in timekeeping, building giant obelisks in 3500BC to act as giant sundials.

Augustus

In 8BC the Roman senate gave ruling emperor August Caesar his own month (August, if that wasn’t obvious…) and added an extra day to match his great uncle Julius Caesar’s month (yep, July!) on 31 days.

Daylight

Throughout World War II citizens in the United States kept their clocks one hour ahead of standard time to allow for longer working hours during daylight.

Minuscule

The world’s smallest atomic clock, built by the National Institute for Standards and Technology, is the size of a grain of rice and accurate to one second in 3,000 years.

Samoa

In May 2011 Samoa decided to move its clocks forward by one day to allow easier trade with Australia and New Zealand, after spending 119 years almost a day behind.

Asked by David Merchant

Many cars were built to compete in the Formula 1 World Championship, but the first one to win it was the Alfa Romeo 158, also known as the Alfetta (‘Little Alfa’ in Italian), in 1950. It was driven by Italian Giuseppe Farina during 1950, in which he won three races out of seven. One of the most successful racing cars ever produced, the 158 and its derivative, the 159, took 47 wins from 54 Grand Prix entered. In the hands of drivers such as Giuseppe Farina, Juan-Manuel Fangio and Luigi Fagioli, it dominated the first two seasons of the Formula 1 World Championship. It was capable of driving at 290km/h (180mph).

Alastair Dodds, Principal Curator of Transport at National Museums Scotland

1835

• Samuel Morse made the first working electric telegraph to send and receive complex messages, and in 1844 he sent the first message: “What hath God wrought?”

1973

• Motorola engineer Dr Martin Cooper made the first handled mobile phone to call to his invention rival Joel Engel at AT&T in 1973.

1985

• First-generation (1G) mobile phones entered the market in the Eighties; they were large and heavy devices with limited battery lives that could only make voice calls.

1992

• The introduction of the 2G network allowed for text messaging and basic Internet access, and by 1999 76% of the UK owned a mobile phone.

2001

• Japan launched the first 3G network, bringing with it faster mobile Internet, and by 2007 there were a total of 200 million 3G users worldwide.

• Sputnik 1

Russia stunned the world in October 1957 when it announced it had placed the first man-made object in orbit around the Earth, the basketball-sized Sputnik 1.

• Explorer 1

America replicated the success of Russia three months later when it launched its first satellite, Explorer 1, which discovered the belts of radiation around Earth.

• Echo 1

NASA launched this giant balloon, 30 metres in diameter, in 1960. It reflected incoming signals and was the world’s first rudimentary communications satellite.

• Satcom

Developed by RCA Americom, Satcom 1 (launched 1975) pioneered US cable TV broadcasts with high-profile networks and spurned the age of satellite TV.

• ISS

Construction of the world’s largest man-made satellite began with the launch of the Zarya module in 1998, and is scheduled for completion in mid-2012.

Gagarin’s Mission

On 12 April 1961, Yuri Gagarin became the first human in history to reach low-Earth orbit, otherwise known as ‘space’. He travelled there inside a metal sphere called Vostok 1, the world’s first manned spacecraft, beating American Alan Shepard into space by just 25 days.

Vostok 1 was a spherical cabin, coated entirely in an ablative material to act as a heat shield as it re-entered the atmosphere. There was a window out of which Gagarin could view the Earth, and an ejector seat for his return (as he would separate from the capsule as it re-entered the atmosphere). Beneath Vostok 1 was a service module containing the chemical batteries and rockets to maneuver the spacecraft. After almost one complete orbit of Earth, lasting 68 minutes, the spacecraft re-entered the atmosphere and landed in Kazakhstan an hour and 48 minutes after launch.

As Gagarin ejected from the spacecraft before it landed, under FAI (Fédération Aéronautique Internationale) rules it did not qualify as an actual space flight, although the Russians kept this quiet for several years after. Nonetheless, Gagarin was still the first human to venture into space.

Check out the front page of the American newspaper The Huntington Times from the day Gagarin completed his famous mission on the left. Below, you’ll find an annotated diagram of Vostok 1.

On the next page we’ve got two astronomically detailed infographics telling you all about Yuri’s journey through the heavens and a look back at 50 years of space travel. But first, you’ll want to check out the video below. It’s an incredible piece of work taken by astronaut Paolo Nespoli aboard the ISS in 2010 that shows almost the exact view Gagarin would have had from his spherical ship as he rattled around the Earth.

Neolithic times

The earliest fire-making method consisted of twirling a pointed stick in a wooden block, creating an ember to light tinder. Iron pyrite rocks were also struck against flint.

Solar power

Using reflective surfaces to focus sunlight on tinder was known in ancient times. Experiments with mirrors/lenses were conducted to develop deadly weapons.

Tinderbox

In the Middle Ages, it was found that a spark is created by striking steel and flint. The portable tinderbox caught the spark in tinder and then ignited a small piece of wood.

Friction matches

English chemist and apothecary John Walker sold the first friction matches in 1827. They could be ignited by striking the head of the match against any rough surface.

Safety matches

In 1844, Gustaf Erik Pasch developed the first safety match. The head contained potassium chlorate, reacting when struck against a surface coated with red phosphorus.

1,500 BC

Egyptians refer to Mars as ‘Horus of the Hawk’, a god with the head of a hawk. They note its retrograde motion, when it moves backwards in its orbit relative to Earth

350 BC

Aristotle first proposes that Mars orbits at a further distance than the moon when he notes that the moon passes in front of Mars in his observations.

1609

Galileo Galilei uses a telescope to become the first person to directly observe Mars, but is later vilified by the Vatican for asserting that the planets orbit the Sun and not earth.

1666

Astronomer Giovanni Cassini calculates the length of a Martian day, notes the polar ice caps and even calculates its distance from Earth in his telescopic observations.

1840

Astronomers Wilhelm Beer and Johann Heinrich Mädler study Mars through a 3.75-inch telescope and produce the first sketched Map of its surface.