Asteroids are small, rocky objects that orbit the Sun and were typically formed during the solar system’s development
Astronomers have issued a stark warning about a concerning group of ‘invisible’ asteroids that could threaten Earth in the distant future. These objects, while not yet spotted through telescopes, are thought to have the potential to crash into our planet and wreak havoc on major cities within a ‘few thousand years’.
The peer-reviewed study, led by Brazil’s São Paulo State University, combined numerical simulations and state-of-the-art models to better grasp the dynamics of these objects over time. Worryingly, they claimed that during ‘transition phases’, occurring roughly every 12,000 years, these asteroids reach ‘extremely small distances from Earth’s orbit’ and risk ‘crossing it’.
Professor Valerio Carruba, an astronomer and the study’s first author, explained: “Our study shows that there’s a population of potentially dangerous asteroids that we can’t detect with current telescopes. These objects orbit the Sun but aren’t part of the Asteroid Belt, located between Mars and Jupiter.
“Instead, they’re much closer, in resonance with Venus. But they’re so difficult to observe that they remain invisible, even though they may pose a real risk of collision with our planet in the distant future.”
Asteroids are small, rocky objects that revolve around the Sun. They are significantly smaller than planets and were typically formed during the solar system’s formation.
The asteroids in question have been dubbed ‘Venusian co-orbitals’. According to NASA, Venus is Earth’s nearest planetary neighbour, situated 38 million km away at its closest approach.
Astronomers have identified just 20 Venusian co-orbital asteroids as of now, but they believe a much larger population remains virtually invisible from Earth. The more ominous asteroids pose the greatest threat to Earth, according to their estimates.
“Asteroids about 300 meters in diameter, which could form craters 3 to 4.5 kilometres wide and release energy equivalent to hundreds of megatons, may be hidden in this population,” Professor Carruba continued.
“An impact in a densely populated area would cause large-scale devastation.” Current simulations suggest that even the brightest asteroids would only be visible for one or two weeks if they appeared 20 degrees above Earth’s horizon.
These short visibility periods are separated by extended intervals during which they cannot be observed. In light of these discoveries, astronomers suggest employing space telescopes to focus on regions closer to the Sun.
Professor Carruba summarised: “Planetary defence needs to consider not only what we can see, but also what we can’t yet see.” The research was carried out by the Orbital Dynamics and Planetology Group (GDOP) at UNESP, with help from a FAPESP scholarship awarded to Gabriel Antonio Caritá, a team member at the National Institute for Space Research (INPE).
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