Asteroid 2003 MH4: The Colossal Stranger Slipping Past Earth
There are giants out there. Okay, I’m not talking about my husband or some cool fantasy novel I just finished reading, I mean some massive bodies of ancient rock…cold, indifferent, and older than our oceans…drifting through the void of space.
These guys don't rage or plot or steal gold or anything nefarious, they simply move through space with the grace of a silent giant.
And sometimes, they come very, very close.
On May 24 2025, NASA is closely monitoring the flyby of Asteroid 2003 MH4, a behemoth roughly the size of three football fields hurtling toward our planetary neighborhood at 14 kilometers per second, about 31,000 miles per hour for my friends in the USA.
It won’t hit us (don’t start panicking yet!), but it also won’t miss by much.
And that space between impact and miss…that’s where my fascination lives.
That’s where science, anxiety, and awe all converge.
What We Know About Asteroid 2003 MH4
LDiscovered in 2003 and tracked ever since, MH4 belongs to a group of objects known as Near-Earth Objects (NEOs). A lot less cool than UFOs, but it is what it is. These guys are celestial bodies (mostly asteroids and comets) that orbit close enough to pose potential threats.
MH4 is estimated to be 300–350 meters in diameter, weighs millions of tons, has an elliptical orbit that crosses Earth’s path every few years, and is officially categorized by NASA as a “Potentially Hazardous Asteroid” (PHA) due to its size and its proximity. Sorry about all the abbreviations and acronyms, I don’t name these things.
On May 24, it will pass within roughly 4.5 million miles of Earth, and that might sound like a lot…but in cosmic terms, it’s a near miss.
NASA doesn’t use the word “hazardous” lightly.
To earn that title, an object must be larger than 140 meters and come within 7.5 million kilometers (4.65 million miles) of Earth. MH4 checks both boxes. Its orbit is close, its mass is enormous (not that I’m shaming it), and even though the trajectory this time is safe, the nature of orbits is that they can change, nudged by gravitational forces from planets or other asteroids at the last minute.
That’s why NASA’s Planetary Defense Coordination Office, which is a real thing, watches objects like MH4 with such intense scrutiny. A slight deflection could turn a near-miss into a direct hit decades from now.
When you're dealing with a rock moving 10 times faster than a bullet, there are absolutely no do-overs.
What Would Happen If It Hit?
Not to get too gloomy or anything, but I’ve always loved movies where asteroids crash down onto the planet, so of course my mind went here immediately. If MH4 were to strike Earth, the results would be catastrophic, but not extinction-level.
This isn’t a dino-killer (that asteroid was 10+ kilometers wide). But it is more than enough to flatten an entire metropolitan area, release more energy than hundreds of nuclear bombs, and trigger massive fires, shockwaves, and tsunamis if it landed in the ocean. Not ideal.
The Tunguska event of 1908…where an asteroid flattened 800 square miles of Siberian forest…was caused by a body only 50–60 meters wide.
MH4 is about six times larger so yeah, more size = more damage.
NASA doesn’t just point a telescope and hope. They use a combination of optical telescopes (to track movement across the sky), radar systems (like Goldstone in California, to bounce signals off the surface and calculate shape, speed, and spin), infrared sensors (to detect heat signatures in space), and orbital modeling software (to predict future paths and potential impacts).
The data is plugged into the Sentry system, which runs continuous calculations for over 28,000 known NEOs.
So far, MH4 has shown no sign of veering toward Earth, but they’ll keep watching, because one wobble…one gravitational nudge…and everything changes.
How Many of These Are Out There?
Too many is the super precise answer you’re looking for.
NASA estimates there are over 1,200 known Potentially Hazardous Asteroids, round 26,000 NEOs total, and possibly hundreds of thousands more we haven’t spotted yet. Those ones we haven’t spotted are obviously the most concerning. Every few weeks though, new asteroids are added to the list and some slip by unnoticed until after they’ve passed.
In 2019, an asteroid the size of a football field passed within 45,000 miles of Earth, and no one saw it until it was too late to react.
It’s like cosmic hide and seek, except we’re not playing, we’re just trying not to lose. So maybe it’s more like paintball or laser-tag?
In case you’re wondering, in 2022, NASA ran its first-ever planetary defense test mission called DART (Double Asteroid Redirection Test). The idea was to smash a spacecraft into an asteroid and see if it can change its orbit. It worked. DART collided with asteroid Dimorphos, reducing its orbital period by 32 minutes. It was a landmark moment…a proof of concept that if we spot danger early enough, we might be able to stop it.
But the key word is early, and we can’t deflect what we can’t detect.
That’s why missions like NEO Surveyor (scheduled to launch by 2028) are critical. It will use infrared telescopes to find asteroids before they sneak up on us.
A Story as Old as Earth
Our planet bears scars all over the place if you know where to look.
Meteor Crater, Arizona: A mile-wide impact site from a 50-meter iron meteorite 50,000 years ago.
Chicxulub Crater, Mexico: A 110-mile wide crater left by the asteroid that ended the reign of the dinosaurs.
Chelyabinsk, Russia (2013): A 20-meter asteroid exploded in the atmosphere with the force of 30 Hiroshima bombs. Over 1,500 people were injured…mostly from shattered windows.
Space is not empty, it’s a shooting gallery, and Earth…is not always lucky.
There’s something deeply intoxicating about asteroids that always drew me in. They remind me that we’re not the center of anything and life can be disrupted in an instant.
The universe doesn’t owe us warning, and yet…there’s beauty in that too.
With every near miss, we gain knowledge. Every flyby that happens, we calibrate our little maps for the future.
With every chill down our spine, we remember that we’re part of something vast, ancient, and wild. I just truly love that thought.
Fun Facts
Asteroid 2003 MH4 is likely a C-type asteroid, made of carbonaceous material, some of the oldest stuff in the solar system.
The Yarkovsky effect (a subtle force caused by sunlight heating one side of a rotating asteroid) can alter orbits over decades.
NASA classifies any object over 1 kilometer wide as a planet killer, which sounds both bad-ass and terrifying (I happen to live on a planet). MH4 is not in that range, but close enough to worry.
Most of Earth’s meteorites come from the asteroid belt, flung inward by gravitational tugs from Jupiter and Mars.
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Want to track space from your own backyard?
Explore the stars with this highly rated beginner telescope for deep sky viewing and track the Moon, Mars, and maybe one day, spot your own asteroid. That would be cool! Once when my grandma and I were outside using my telescope we did see something that looked like an asteroid fall sort of nearby us.
We’re not in control here, not really. We launch satellites and predict eclipses, while someone in a room somewhere runs calculations so precise they make your head ache, but in the end, we’re still a spinning blue dot…suspended in a universe that doesn’t even flinch when a rock the size of a skyscraper whistles past our cheek.
And maybe that’s why we keep looking up, because it reminds us we’re still here, still watching the shadows pass…and whispering prayers into the void.
