June 30, 2015, marked the first Asteroid Day, which organizers described as a “global awareness movement where people from around the world come together to learn about asteroids and what we can do to protect our planet” from asteroid and comet impacts.
This year’s Asteroid Day has planned events worldwide and online. Even Google is recognizing the event — you can see how when you search “Asteroid Day.”
June 30 is a significant date in the history of Earth impacts. On that date in 1908, the “Tunguska Event” occurred over Tunguska, Russia. A stony (not icy) body between 165 and 260 feet in diameter entered the atmosphere at around 33,500 mph, creating a 4-megaton explosion, about 3 to 6 miles above the ground, more than 250 times more powerful than the atom bomb dropped on Hiroshima, according to earthsky.org.
The Tunguska Event devastated 830 square miles, and 80 million trees were flattened, according to NASA. This is the largest event with such impact in modern history and is why Asteroid Day is observed every year on June 30 as a reminder to the world that planetary defense against asteroids and comets matters.
The Chelyabinsk impact event in 2013 was historic because of the number of injuries and damage it caused to buildings — the most ever recorded from an asteroid or meteorite event. It was also the most documented asteroid explosion and meteorite fall ever with the number of videos, sound recordings, photographs, witness interviews and the recovery process of meteorites.
Chelyabinsk also improved our knowledge of the threat posed by asteroids smaller than a kilometer. These smaller asteroids like Chelyabinsk may be a greater hazard for damage than previously thought. In December 2018, an event with 40% of the energy release of Chelyabinsk took place over the Bering Sea, as reported by BBC, reaffirming that such events happen more often than we would like.
Efforts by the United Nations, NASA, the European Space Agency and the B612 Foundation continue to improve the detection of asteroids and develop a defensive capability.
Advances in planetary defense
There have been some recent highlights in planetary defense that have significantly improved Earth’s ability to detect and deflect an asteroid.
The Vera Rubin Observatory is now operational and capable of discovering millions of new asteroids. During its inaugural “First Look” last summer, 2,104 new asteroids were discovered.
The James Webb Space Telescope has made discoveries about our asteroid belt and those around other stars.
Citizen scientists recently discovered 1,000 asteroids using data from the Hubble Space Telescope.
NASA established a Planetary Defense Coordination Office.
Interagency exercises, including the fifth biennial Planetary Defense Interagency Tabletop Exercise held in Maryland, are testing real world scenarios and responses regularly.
NASA’s NEO Surveyor mission, approved in 2021, that is designed specifically for finding asteroids — especially those near the sun and difficult to spot by telescopes — like Chelyabinsk. Principal Investigator Dr. Amy Mainzer told WTOP last June, “We’re excited to ramp up work on the spacecraft bus starting this fall in preparation for launch in September 2027.”
NASA’s Double Asteroid Redirection Test successfully changed the orbit of an asteroid in September 2022.
The European Space Agency’s Hera mission is scheduled to arrive at the DART target system in November, where it will study the results of humanity’s first asteroid-deflection test.
According to the space agency’s website, “As part of the world’s first test of asteroid deflection, Hera will perform a detailed post-impact survey of the target asteroid, Dimorphos – the orbiting moonlet of a binary asteroid system known as Dimorphos. Now that NASA’s DART mission has impacted the moonlet, Hera will turn the grand-scale experiment into a well-understood and repeatable planetary defense technique.”
A worldwide community of citizen astronomers, working with the SETI Institute, are also participating in planetary defense by making real time observations using telescopes made by Unistellar. Anyone with a telescope can participate as well.
One final thought:
“The dinosaurs are dead because they didn’t have telescopes or a space program.”
I use this phrase of mine to remind audiences why planetary defense is important. The dinosaurs disappeared after an asteroid struck the Yucatán Peninsula about 66 million years ago.
The cosmic clock is ticking.
If we need a reminder, we got one just last weekend when a large asteroid passed by earth.
Asteroid Day — become part of the movement.
Follow Greg Redfern’s daily blog to keep up with the latest news in astronomy and space exploration.
Get breaking news and daily headlines delivered to your email inbox by signing up here.
© 2026 WTOP. All Rights Reserved. This website is not intended for users located within the European Economic Area.
