Our Biggest Spherule Looks Like an Alien Emoji

Avi Loeb
4 min readJun 23, 2023


Diary of an Interstellar Voyage, Report 24 (June 23, 2023)

Spherule number 15 from today’s Run 13 is the biggest yet and looks like a skull or an alien emoji. With a size of 0.6 millimeters, it exhibits cavities on its surface. Its composition is dominated by iron plus elements used in electronic circuitry.

At a planning meeting for our next expedition, I had asked Rob McCallum: “When should we open the champagne in celebration of the spherule harvest of this expedition?” Rob reasoned: “We need to assign a reasonable threshold for the number count of spherules”, to which I responded “15”.

A few minutes later, I was looking over the shoulders of Ryan Weed as he examined a new spherule candidate from the latest Run 13 under the microscope. This constituted the biggest candidate spherule we had so far, measuring 600 microns in diameter, twice the size and up to 8 times the mass of the previous record holder. This object was scarred with cavities, resembling an alien emoji. We were unsure whether it is biological and decided to cast the verdict by inferring its composition with the X-ray Fluorescence (XRF) analyzer. The XRF reading implied mostly iron plus trace elements used in semiconductors. Was this alien-emoji-looking spherule part of electronic circuitry? Follow-up analysis is needed.

Irrespective of its unknown origin, one thing became clear: with the help of the new anomalous spherule, we surpassed the spherule count threshold of 15 for opening the champagne. I informed Rob of the occasion and we decided to celebrate tomorrow because of an imminent sled recovery effort for Run 14. This spherule recovery effort took place in heavy rain and was accelerated by a vacuum cleaner.

The spherule recovery effort for Run 14 took place in the pouring rain. From left: J.J. Siler, Avi Loeb, Charles Hoskinson, Amir Siraj, Ryan Reed and the audio recorder for the film, Sean Huntley.

Just before these events, I had received an unexpected email about my last diary report, titled “What a Beautiful World.” The message took me by surprise and gave a new sense of purpose to our effort:

Hello Avi,

“What a wonderful world” Yes, you are right Avi! I had a heart attack four weeks ago and am now in rehab. I read your IM1 diary every day and it always gives me new courage to face life. There are still so many things to discover and I want to live long enough to see some of them. I wish you and your team all the best.

Life can be damn beautiful!

Best regards …

To which I immediately replied:

Dear …,

Thank you so much for your kind words.

Long live and prosper! I will do my best to make life worth living.

With warmest wishes to you from the Pacific Ocean,


Our expedition team came to the Pacific Ocean, motivated by a genuine curiosity to explore the unknown. We are now harvesting the fruits of this heroic team effort.

Towards the end of our planning meeting, we decided to make a stop at the world’s best gamma-ray spectrometer on our way home from Silver Star a week from now. This world-class spectrometer offers a sensitivity that is a hundred times better than the one we are currently using on the ship. Since the signal-to-noise ratio improves in proportion to the square-root of the integration time, we will be able to achieve in 10 seconds the sensitivity that we currently reach in a day on Silver Star. The spectroscopic signatures of various radioactive isotopes will allow us to test the interstellar origin of IM1 and also constrain the duration of its journey. Multiplying this journey time by IM1’s velocity, we could constrain the 3D location of its source star.

The expedition team member, Jeff Pugh, vacuums the mix of volcanic ash and spherules out of the sled magnets of Run 12 on the deck of Silver Star. The collected material is later analyzed by the team’s instruments.

Our 15 spherules were retrieved from a depth of about 2 kilometers, where they rested for nearly a decade after arriving at the Pacific Ocean on January 8, 2014 as the fireball’s molten relics.

The fundamental question is whether the meteor was natural or technological in origin, given its anomalously high speed, unusual material strength and anomalous elemental composition — possibly resembling that of electronic circuitry for the alien-emoji-like spherule. We hope to answer this question by an exquisite analysis of isotopic composition and radioactive dating.

The census of IM1’s spherules includes one from Runs 6, nine from Run 8, two from Run 9, and one from Runs 12 and 13. We plan to use the spherule counts and the associated sled lines to localize IM1’s path and circle the likely location of any large remnant that survived the crash on the ocean floor. Our ultimate goal is to retrieve this remnant if it exists. We use spherules to lead us to our interstellar partner, as if they were a romantic trail of rose petals.


Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He chairs the advisory board for the Breakthrough Starshot project, and is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. His new book, titled “Interstellar”, is scheduled for publication in August 2023.



Avi Loeb

Avi Loeb is the Baird Professor of Science and Institute director at Harvard University and the bestselling author of “Extraterrestrial” and "Interstellar".