A Billion Years In Interstellar Space: What We Know Today About ‘Oumuamua
“The incredible conclusion isn’t just that ‘Oumuamua came from outside
of our Solar System, but that this was both rare and common. For an
individual object, like ‘Oumuamua, it will likely never come this close
to another Solar System again. Only once every 100 trillion years — some
10,000 times the current age of the Universe — will it pass so close to
a star. As scientist Gregory Laughlin put it, “this was the time of
But for our Solar System, because of the sheer
number of objects like this flying through the galaxy, we probably
experience a close encounter like this around a few times per year. 2017
marked the first time we saw such an object, but we’ve likely gotten
billions of them over the course of our Solar System’s lifetime. Some of
them, if nature was kind, may have even collided with Earth.
There may be as many as ~1025
of objects like this flying through our galaxy, and every so often,
we’ll get lucky enough to encounter one of them. For the first time,
we’ve actually seen one of them for ourselves.”
In 2017, our Solar System received a visit like never before: from an object originating from interstellar space. Likely ejected more than a billion years ago from a foreign solar system, it happened to pass within even the orbit of Mercury, only becoming visible to our telescopes when it came within 60 lunar distances of the Earth.
But we found it, observed it, and learned everything we could about it. What do we know, today? Spoiler: it’s not from aliens.
Starts With A Bang #38 — Interstellar Interloper `Oumuamua
The first identified visitor from another solar system gets its own Starts With A Bang podcast!
In 2017, the incredible happened: for the first time in history, we were able to identify an object passing through our Solar System that originated from outside of it! Interstellar interloper ‘Oumuamua was originally designated as a comet, then as an asteroid, and then as a new class of object: one of interstellar origin. It’s a fascinating object that’s the first of its kind, and much has been said about its composition, properties, and possible nature.
But, unfortunately, the most famous of those “nature” discussions was from Schmuel Baily and Avi Loeb of Harvard, claiming that it could be due to aliens.
Is that plausible? Is that even science? My guest for this edition is astrophysicist Paul Matt Sutter, author of the new book Your Place In The Universe, and we have an almost-hour-long discussion that goes to some fantastic and unexpected places. You won’t want to miss it!
The Starts With A Bang Podcast is made possible through the donations of our Patreon supporters, who get it early, get shout-outs, and much more!
Find Paul online on Twitter twitter.com/PaulMattSutter,
Book: Your Place In The Universe amzn.to/2DCysNj
Interstellar Visitor ‘Oumuamua Was Shaped By Cosmic Particles
“We think of space as being an empty place, but the truth is that there are dust grains, particles, neutral atoms, ions, and cosmic rays zipping through the entirety of the galaxy, even when there are no stars. As an object moves through space, circling the galaxy at hundreds of kilometers per second (and moving relative to most other objects at tens of kilometers per second), it’s constantly bombarded by large numbers of small, fast-moving bits of matter. Just as water and sand will smooth out and erode pebbles and cobbles in the ocean here on our world, the cosmic equivalent — the interstellar medium — will have the same effect over extremely long timescales on ejected icy bodies.”
When scientists discovered ‘Oumuamua last year, they were surprised to find that it not only originated from outside our Solar System, but possessed bizarre properties we had never seen before. It was extremely elongated, tumbled irregularly, and had a never-before-seen composition: a carbon crust over an icy interior. Despite heating up to 550 °F (290
°C), it never developed a tail, a coma, or showed any ejecta. Many have proposed exotic or recent origins for this interstellar interloper, but in this case, simplicity rules: it may just be a cosmic pebble in the galactic sea. The interstellar medium is full of particles, and ‘Oumuamua, like most interstellar objects, should move at about 0.01% the speed of light through the galaxy. Over time, it should be worn down in exactly the fashion we see. As we discover more objects with an origin beyond our Solar System, we fully expect they’ll appear quite similar to this one.
How was ‘Oumuamua shaped? Likely by cosmic particles, rather than anything exotic. Come find out the science behind how.