As scary as an incoming asteroid may sound, it doesn’t have to mean the end of the world. It’s true space rocks sometimes collide with our planet, as happened with devastating effect 66 million years ago when a massive impact wiped out the dinosaurs. But such events are the exception rather than the rule. By astronomical standards, Earth is a very small target. Asteroids move on precisely determined orbits, so the vast majority of them simply whiz past the planet at a safe distance. Such encounters are a good thing for astronomers because they give them a chance to study asteroids at close range, and these small, rocky objects can tell us a lot about the origin and evolution of the Solar System. When the first asteroids were discovered, they were all found to lie in an ‘asteroid belt’ between the orbits of Mars and Jupiter. It’s still true today that most known asteroids are located in this region.
Asteroids can be thought of as miniature planets, a few metres to several thousand metres in size, which move on a range of orbits around the Sun in much the same way planets do. All these orbits have a similar basic shape: a kind of distorted circle called an ellipse. The point on the ellipse that’s furthest from the Sun is called aphelion, while the closest is perihelion. In the case of a planet like Earth, the difference between perihelion and aphelion is very small, which means that the orbit is almost circular. Asteroid orbits, on the other hand, can be much more eccentric than this, and some of them can actually have a perihelion inside Earth’s orbit and an aphelion outside it. In other words, their orbits around the Sun overlap with our own planet’s.
This story is from the Issue 178 edition of How It Works UK.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the Issue 178 edition of How It Works UK.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber? Sign In
COULD A SUPERNOVA WORDS ANDREW MAY ENGULF EARTH?
We put some intriguing, baffling and bizarre space questions under the spotlight
Understanding MENTAL HEALTH
Take a tour of the brain to discover the origins of anxiety and how to tackle it
DNA reveals that ancient American lineage goes back 18,000 years
Members of the Blackfoot Confederacy have an ancient lineage that goes back 18,000 years. This means that Indigenous peoples living in the Great Plains of Montana and southern Alberta today can trace their origins to ice age predecessors.
A sleeping subduction zone could swallow the Atlantic
A subduction zone below the Gibraltar Strait is creeping westward and could one day ‘invade’ the Atlantic Ocean, causing the ocean to slowly close up.
An underwater mountain hosts creatures unknown to science
An underwater mountain chain off Rapa Nui, also known as Easter Island, hosts an astonishing array of deep-sea species, at least 50 of which are new to science.
A group of 60 ultra-faint stars could be a new type of galaxy
A stronomers have spotted the faintest and lightest satellite galaxy ever found: a minuscule, tight-knit group of stars trailing the Milky Way.
A drone with a rotating detonation rocket engine' approached the speed of sound
venus Aerospace has completed the inaugural test flight of a drone fitted with its rotating detonation rocket engine (RDRE), accelerating it to just under the speed of sound.
HOW STONEHENGE WAS BUILT
Who built this stone circle and how was this ancient feat of engineering pulled off?
ANIMALS ON THE BRINK
Meet some of the most critically endangered animals from around the world and discover why they're on the brink of extinction
WHAT ARE ULTRAPROCESSED FOODS?
Some natural products are drastically transformed by the food industry, and regularly eating them can affect our health