L’anno scorso, l’asteroide più pericoloso conosciuto dall’umanità non colpirà la Terra per almeno 100 anni.

L’asteroide 2021 QM1 è stato ufficialmente rimosso dall’elenco degli asteroidi dell’ESA. Sono rimasti 1377 asteroidi. (L’impressione dell’artista di un asteroide che vola sulla Terra).

Impatto escluso nel 2052 poiché l’Agenzia spaziale europea (ESA) calcola il giorno degli asteroidi

Al momento giusto per la Giornata Mondiale degli Asteroidi. La minacciosa roccia spaziale è rimasta in cima alla lista dei rischi per mesi in tutto il mondo con una reale possibilità di colpire la Terra il 2 aprile 2052. Attualmente, il team di asteroidi dell’ESA sta lavorando con esperti dell’Europa meridionale. Osservatorio ([{” attribute=””>ESO) has officially removed ‘2021 QM1’ from their asteroid risk list, a result of skilled observations and analysis of the faintest asteroid ever observed with one of the most sensitive telescopes ever constructed.

With Asteroid Day Live 2022 set for June 30, we can safely say that the riskiest asteroid known to humankind in the last year will not impact the Earth – at least not for the next century.

What was it like to track this asteroid? Get the full story in ESA’s fascinating behind-the-scenes look at how European experts handle asteroid risks in the official countdown to Asteroid Day live on June 30, airing at 10:25 CEST on AsteroidDay.org and via ESA WebTV.

Stars Hide Once-Risky Asteroid 2021 QM1

Asteroid 2021 QM1, once thought to have a chance of impacting Earth in 2052, was spotted passing through a region of the sky with the Milky Way just behind it. The small, faint, receding asteroid had to be found against a backdrop of thousands of stars, with red crosses indicating the path of the object. Credit: ESO/O. Hainaut

Impact 2052

2021 QM1 was first discovered on August 28, 2021, by the Mount Lemmon Observatory, located north of Tucson, Arizona. At the beginning, nothing stood out as unusual about the discovery – about a dozen new near-Earth asteroids are identified every dark night. Routine follow-up observations were subsequently acquired from telescopes around the globe, but these began to tell a more worrying story.

“These early observations gave us more information about the asteroid’s path, which we then projected into the future,” said Richard Moissl, ESA’s Head of Planetary Defense.

“We could see its future paths around the Sun, and in 2052 it could come dangerously close to Earth. The more the asteroid was observed, the greater that risk became.”

Si può notare che i calcoli dell’orbita basati su poche osservazioni notturne sono soggetti a qualche incertezza, motivo per cui gli asteroidi vengono spesso aggiunti all’elenco dei rischi dell’ESA non appena vengono rilevati e quindi rimossi quando vengono raccolti dati aggiuntivi. e l’asteroide si è dimostrato sicuro. Non è stato possibile in questa occasione.

Disposizione dello spazio non riuscita

Non appena il rischio aumentava, si verificava un (non) perfetto allineamento cosmico. Il percorso dell’asteroide lo ha avvicinato al Sole, come sembrava dalla Terra, էր è stato impossibile vederlo per mesi a causa del bagliore luminoso della nostra stella ospite.

Orbita dell'asteroide 2021 QM1

L’orbita del 2021 QM1 mentre passava nel cielo più vicino al Sole, visto dalla Terra, subito dopo la sua scoperta. Credito: ESA

“Dovevamo solo aspettare”, ha affermato Marco Micheli, astronomo del Near-Earth Object Coordination Center (NEOCC) dell’ESA.

“Ma per limitare tutto, sapevamo che anche il QM1 del 2021 stava lasciando la Terra nella sua orbita attuale, il che significa che quando passa attraverso il Sole, potrebbe essere troppo debole per essere rilevato”.

Mentre aspettavano, si preparavano.

Primo accesso a uno dei telescopi più potenti sulla Terra

Il Very Large European Observatory (VLT) era pronto և pronto. Non appena l’asteroide di 50 metri esce dalla luce, se le condizioni meteorologiche lo consentono, il VLT dell’ESO concentrerà il suo specchio di 8 metri sulla roccia che sta scomparendo.

Drammatica madre lunare con il telescopio molto grande dell'ESO!

Luna drammatica dietro il VLT (Very Large Telescope) dell’ESO, Cile. Quando la luna piena entra nella madre, il Sole sta per sorgere sull’orizzonte opposto. Il Very Large Telescope (VLT) ha già chiuso gli occhi dopo una lunga notte di osservazione, և operatori del telescopio e astronomi dormono, mentre tecnici, ingegneri և astronomi diurni si stanno svegliando per una nuova giornata di lavoro. L’azione non si ferma mai all’osservatorio astronomico terrestre più efficiente del mondo. Prestito: G.Gillet / ESO

“Avevamo una breve finestra dove potevamo vedere il nostro rischioso asteroide”, ha detto Olivier Hainaut, un astronomo dell’ESO.

“Quando è peggiorato, ha attraversato un cerchio nel cielo[{” attribute=””>Milky Way just behind. Our small, faint, receding asteroid would have to be found against a backdrop of thousands of stars. These would turn out to be some of the trickiest asteroid observations we have ever made”.

Faintest asteroid ever observed

Over the night of May 24, ESO’s VLT took a series of new images. The data arrived and Olivier and Marco began to process them, stacking subsequent observations on top of each other and removing the background stars: it took some time.

VLT Asteroid 2021 QM1

ESO’s Very Large Telescope captures 2021 QM1 which for months topped risk lists around the globe. This pivotal sighting ruled out Earth impact in the year 2052. Over the night of May 24, the European Southern Observatory’s Very Large Telescope took a series of images of an asteroid that had topped risk lists around the globe for months. These images were some of the trickiest asteroid experts had taken, as the faint asteroid 2021 QM1 receded from view against a very starry backdrop. A series of images were processed, stacked on top of each other and stars were removed, revealing the faintest asteroid observed. Credit: ESA

The result? A positive detection of the faintest asteroid ever observed. With a magnitude of 27 on the scale used by astronomers to describe the brightness of objects in the sky, 2021 QM1 was 250 million times fainter than the faintest stars visible to the naked eye from a dark spot. (In this astronomical scale of visible magnitudes, the brighter an object appears the lower the value of its magnitude, while the brightest objects reach negative values, e.g. the Sun is magnitude -27).

Olivier was certain this small blur was in fact an asteroid, and Marco was certain that given its location, it was our asteroid.

Safe at last?

With these new observations, our risky asteroid’s path was refined, ruling out an impact in 2052, and 2021 QM1 was removed from ESA’s risk list. Another 1,377 remain.

Asteroids June 2022 With Gaia

The position of each asteroid at 12:00 CEST on June 13, 2022, is plotted. Each asteroid is a segment representing its motion over 10 days. Inner bodies move faster around the Sun (yellow circle at the center). Blue represents the inner part of the Solar System, where the Near Earth Asteroids, Mars crossers, and terrestrial planets are. The Main Belt, between Mars and Jupiter, is green. The two orange ‘clouds’ correspond to the Trojan asteroids of Jupiter. Credit: © ESA/Gaia/DPAC; CC BY-SA 3.0 IGO, Acknowledgments: P. Tanga (Observatoire de la Côte d’Azur)

More than one million asteroids have been discovered in the Solar System, almost 30 000 of which pass near Earth, with many more expected to be out there. ESA’s Planetary Defence Office, NEOCC and astronomers around the globe are looking up to keep us safe, working together to ensure we know well in advance if an asteroid is discovered on a collision course.

Watch Asteroid Day Live

How worried are the world’s asteroid experts? How did it feel to track humankind’s most risky asteroid? Get the full story in ESA’s 30-minute program counting down to Asteroid Day live on June 30, airing at 10:25 CEST on AsteroidDay.org and on ESA WebTV.

Tunguska Devastation

Fallen trees at Tunguska, Imperial Russia, seen in 1929, 15 km from epicenter of the aerial blast site, caused by the explosion of a meteor in 1908. Credit: Photo N. A. Setrukov, 1928

Asteroid Day is the United Nations-sanctioned day of public awareness of the risks of asteroid impacts, held annually on June 30. This year sees its return to Luxembourg for an in-person event following two years of living entirely in the virtual realm. Asteroid experts from ESA, from across Europe and worldwide will converge on the city to take part in a packed four-hour live program of panels and one-on-one interviews.

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