Category: interstellar

Goodbye ‘Oumuamua, Hello Borisov; This Is What Two Interstellar Interlopers Can Teach Us

“The most interesting aspect of what we know so far about interstellar objects is how different the first two, ‘Oumuamua and Borisov, truly are from one another. There are a number of ways to form interstellar bodies: from failed star systems in star-forming regions, from ejected asteroids, from comets, and from collisional debris. We do not know how common or rare objects of all these different types are, nor how to definitively classify the ones we’ve seen so far, but hope is on the way. Beginning in the 2020s, the Large Synoptic Survey Telescope will come online, expected to uncover dozens of such objects by 2030.

What are the size and frequency distributions of the interstellar population? How old and/or weathered are they? Are they comet-like or asteroid like; volatile-rich or volatile-free, and do different classes of object originate from different regions in the sky? Are most small objects inactive while most large ones are active? With the tip of the interstellar iceberg uncovered, the answers to these questions and more are at last within our reach.”

In our solar system, asteroids, centaurs, comets, Kuiper belt and Oort cloud objects all have their own unique story, but possess many qualities common to each separate class. Occasionally, one of these objects will get ejected, where it will wander the Milky Way indefinitely, until it encounters another object.

Back in our Solar System, we’ve begun discovering and identifying objects in our neighborhood that originated from interstellar space. In 2017, ‘Oumuamua became the first, and it was extremely odd: small, elongated, and already on its way out. Our picture is now changing dramatically, as a second interstellar object, 2I/Borisov, was just discovered.

With its closest approach coming in early December, astronomers worldwide are getting ready. Here’s what we know so far.

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,
Video: www.pmsutter.com/shows/askaspaceman/,
Book: Your Place In The Universe amzn.to/2DCysNj

Ask Ethan: Which Movies Get The Science Of Time Travel Right?

“I’m admittedly a fan of time-travel movies (however they explain it). What movie makes the best case for using this plot device accurately?”

Time travel has been a staple of fiction for centuries, as the notion of either traveling forward in time to explore the future or back in time to right a past wrong have been a part of humanity’s imaginings for perhaps always. But we have explicit laws and rules for traveling through time, and how our motion through space affects it. In General Relativity, the possibilities of wormholes and closed-timelike-curves arises, opening up a whole new set of avenues for success. From Bill & Ted’s excellent adventure to Idiocracy, from Harry Potter and the Prisoner of Azkaban to Interstellar, and from Back to the Future to Groundhog Day, the science of time travel is one of the most fascinating ones out there.

Which movies get it right, and which ones get it egregiously wrong? Find out what my evaluations are on this edition of Ask Ethan!

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.

Ask Ethan: What Science Experiments Will Open The Door To The Future?

“Provided that we have some luck, what science experiments that are going to happen withing a couple of decades could open us a way to build some sci-fi movie tech?”

The dream of futuristic technologies and what they might enable us to do – travel back in time, create artificial gravity, traverse the stars, create unlimited energy – are some of the best goals science can aspire to. While a great many of the technologies we’ve envisioned might well prove to be physically impossible, these four could immediately become reality if just one experiment, potentially within the next decade, reveals a surprise it should be able to detect. If dark matter is detected and proves to be its own antiparticle, then all we need to do is figure out how to harness it and unlimited fuel along an interstellar journey is ours for the taking. Antimatter might fall upwards in a gravitational field, having a negative mass, which would create artificial gravity and even, potentially, warp drive. And if the Universe rotates with just the right value, traveling back in time might become a part of science, not just science fiction.

There are experiments ongoing today and ones presently under design that might unlock these mysteries and more. Find out all about them on this week’s Ask Ethan!