Hanno Rein
@hanno-rein.de
#Astrophysics Professor at the University of #Toronto, Minor Planet 12249, #UTSC, #UofT, developer of the Exoplanet App for #iOS, #pilot, #cycling, #climbing, #running, #Egyptology, #woodworking.
I redid the integration with REBOUND. And it now takes less than a second on my laptop. 😉
Source code: gist.github.com/hannorein/b1...
Source code: gist.github.com/hannorein/b1...
November 11, 2025 at 5:03 PM
I redid the integration with REBOUND. And it now takes less than a second on my laptop. 😉
Source code: gist.github.com/hannorein/b1...
Source code: gist.github.com/hannorein/b1...
💫 @philip-armitage.bsky.social shared a paper from 1965 which first showed numerically that Neptune and Pluto are in a 3:2 resonance. This integration took 100 hours on the Naval Ordinance Research Calculator.
Original paper: ui.adsabs.harvard.edu/abs/1965AJ.....
Original paper: ui.adsabs.harvard.edu/abs/1965AJ.....
November 11, 2025 at 5:03 PM
💫 @philip-armitage.bsky.social shared a paper from 1965 which first showed numerically that Neptune and Pluto are in a 3:2 resonance. This integration took 100 hours on the Naval Ordinance Research Calculator.
Original paper: ui.adsabs.harvard.edu/abs/1965AJ.....
Original paper: ui.adsabs.harvard.edu/abs/1965AJ.....
🎉💫 We had another paper accepted last week. Garett Brown was the lead on this one. We study the effect of a substellar flyby on the Solar System and find that there is a surprisingly high probability that such a flyby could have played an important role in shaping the system's architecture.
November 10, 2025 at 2:27 PM
🎉💫 We had another paper accepted last week. Garett Brown was the lead on this one. We study the effect of a substellar flyby on the Solar System and find that there is a surprisingly high probability that such a flyby could have played an important role in shaping the system's architecture.
🔭💫🎉 New paper accepted and now out on the arxiv:
Early evidence for isotropic planetary obliquities in young super-Jupiter systems
arxiv.org/abs/2511.04091
Early evidence for isotropic planetary obliquities in young super-Jupiter systems
arxiv.org/abs/2511.04091
November 7, 2025 at 3:36 PM
🔭💫🎉 New paper accepted and now out on the arxiv:
Early evidence for isotropic planetary obliquities in young super-Jupiter systems
arxiv.org/abs/2511.04091
Early evidence for isotropic planetary obliquities in young super-Jupiter systems
arxiv.org/abs/2511.04091
Making plans for our walk-in closet.
November 1, 2025 at 9:42 PM
Making plans for our walk-in closet.
We are trying to capture some stray kittens. We got one! There might be up to 4 more.
October 31, 2025 at 9:05 PM
We are trying to capture some stray kittens. We got one! There might be up to 4 more.
Downloads of my Bright Comets app are picking up. This can only mean one thing: There's a bright comet out there! Well, two actually!
Free download: apps.apple.com/gb/app/brigh... #comet #astronomy
Free download: apps.apple.com/gb/app/brigh... #comet #astronomy
October 21, 2025 at 12:34 AM
Downloads of my Bright Comets app are picking up. This can only mean one thing: There's a bright comet out there! Well, two actually!
Free download: apps.apple.com/gb/app/brigh... #comet #astronomy
Free download: apps.apple.com/gb/app/brigh... #comet #astronomy
According to Air Canada's website labour disputes are outside of their control... 🤦♂️
August 17, 2025 at 11:54 AM
According to Air Canada's website labour disputes are outside of their control... 🤦♂️
🔭☄️ By the way, the #interstellar #comet 3I/2025 N1 (ATLAS) is on my free Bright Comets #iOS app, in case you want to know where it is right now. Spoiler: it's still very faint at 16 mag. But it should brighten up to 12 mag by October.
apps.apple.com/us/app/brigh...
#astronomy
apps.apple.com/us/app/brigh...
#astronomy
July 20, 2025 at 3:40 PM
🔭☄️ By the way, the #interstellar #comet 3I/2025 N1 (ATLAS) is on my free Bright Comets #iOS app, in case you want to know where it is right now. Spoiler: it's still very faint at 16 mag. But it should brighten up to 12 mag by October.
apps.apple.com/us/app/brigh...
#astronomy
apps.apple.com/us/app/brigh...
#astronomy
💧🪴 I finally got around to installing the trip irrigation system for the peppers and eggplants. I got all the stuff for free from some stranger on Facebook! And I’ve only used about a quarter of it so far.
July 13, 2025 at 12:09 AM
💧🪴 I finally got around to installing the trip irrigation system for the peppers and eggplants. I got all the stuff for free from some stranger on Facebook! And I’ve only used about a quarter of it so far.
⛈️ I've updated my AltWeatherCAN app. It now includes radar images and a widget for the home screen! I wrote it because I really hate the redesign of Environment Canada's official app. #canada #onstorm #weather
It's open source, free, ad-free, add-on free:
apps.apple.com/us/app/altwe...
It's open source, free, ad-free, add-on free:
apps.apple.com/us/app/altwe...
July 11, 2025 at 12:18 PM
⛈️ I've updated my AltWeatherCAN app. It now includes radar images and a widget for the home screen! I wrote it because I really hate the redesign of Environment Canada's official app. #canada #onstorm #weather
It's open source, free, ad-free, add-on free:
apps.apple.com/us/app/altwe...
It's open source, free, ad-free, add-on free:
apps.apple.com/us/app/altwe...
Specifically, the timestep can be as large as 1/3 of Mercury's orbital period, or ~32days. This works because the Solar System is chaotic and secular, not mean-motion resonances, are driving the evolution.
July 9, 2025 at 3:45 PM
Specifically, the timestep can be as large as 1/3 of Mercury's orbital period, or ~32days. This works because the Solar System is chaotic and secular, not mean-motion resonances, are driving the evolution.
🔌🥵 The electricity grid in Ontario is struggling to keep up with demand in this heatwave. Here's the grid voltage since the beginning of June. It usually fluctuates around 124V but dropped below 122V during the hottest hours of the last few days. In addition we also had a few complete power outages.
June 24, 2025 at 6:20 PM
🔌🥵 The electricity grid in Ontario is struggling to keep up with demand in this heatwave. Here's the grid voltage since the beginning of June. It usually fluctuates around 124V but dropped below 122V during the hottest hours of the last few days. In addition we also had a few complete power outages.
I had a great first back country trip of the year! #iceout #algonquinpark
May 2, 2025 at 11:39 AM
I had a great first back country trip of the year! #iceout #algonquinpark
I went full Matthias Wandel on this #woodworking project: A pine bench that I picked up from the street got its legs extended. Now it's a table! Naturally, I used the worst 2x4 I could find and Matthias Wandel's box joint jig for the joinery.
April 28, 2025 at 1:37 AM
I went full Matthias Wandel on this #woodworking project: A pine bench that I picked up from the street got its legs extended. Now it's a table! Naturally, I used the worst 2x4 I could find and Matthias Wandel's box joint jig for the joinery.
March 22, 2025 at 5:16 PM
Small weekend woodworking project: power outlets under the table and a space to hide all the cables.
March 8, 2025 at 11:55 PM
Small weekend woodworking project: power outlets under the table and a space to hide all the cables.
Just 20 days until the next partial solar #eclipse! It’s visible from parts of Europe and North America. You can download my free “Eclipse Live” app to see if you’re in the path. apps.apple.com/ca/app/solar...
March 8, 2025 at 10:06 PM
Just 20 days until the next partial solar #eclipse! It’s visible from parts of Europe and North America. You can download my free “Eclipse Live” app to see if you’re in the path. apps.apple.com/ca/app/solar...
🔭☄️ The asteroid 2024 YR4 has been in the news lately because it has a 1.3% chance of impacting Earth in 2032.
I wrote up a short example on how to integrate the orbit with REBOUND and ASSIST in this Jupyter notebook:
github.com/hannorein/as...
#2024YR4 #astronomy
I wrote up a short example on how to integrate the orbit with REBOUND and ASSIST in this Jupyter notebook:
github.com/hannorein/as...
#2024YR4 #astronomy
February 1, 2025 at 8:47 PM
🔭☄️ The asteroid 2024 YR4 has been in the news lately because it has a 1.3% chance of impacting Earth in 2032.
I wrote up a short example on how to integrate the orbit with REBOUND and ASSIST in this Jupyter notebook:
github.com/hannorein/as...
#2024YR4 #astronomy
I wrote up a short example on how to integrate the orbit with REBOUND and ASSIST in this Jupyter notebook:
github.com/hannorein/as...
#2024YR4 #astronomy
Many thanks to my (former) students Garett, Dang, Pejvak and Nick, who helped disassemble 16 nodes of the NIAGARA supercomputer today. Everything is now at UTSC and once we've put it back together, my group will have its own small compute cluster with 640 cores.
January 29, 2025 at 2:52 AM
Many thanks to my (former) students Garett, Dang, Pejvak and Nick, who helped disassemble 16 nodes of the NIAGARA supercomputer today. Everything is now at UTSC and once we've put it back together, my group will have its own small compute cluster with 640 cores.