Tony Dunn
@tony873004.bsky.social
Orbit simulations of planets, comets, asteroids and other interesting stuff. Amateur astronomer. BA: Physics & Astronomy, SFSU.
Potentially Hazardous #Asteroid (PHA) 3361 Orpheus is an Apollo-class Near-Earth Asteroid (NEA).
Last night it posed for a 30-minute image taken with my eVscope from San Francisco. Dim, mag 15.9 it is centered in the image. @unistellar.bsky.social
Last night it posed for a 30-minute image taken with my eVscope from San Francisco. Dim, mag 15.9 it is centered in the image. @unistellar.bsky.social
November 1, 2025 at 10:54 PM
Potentially Hazardous #Asteroid (PHA) 3361 Orpheus is an Apollo-class Near-Earth Asteroid (NEA).
Last night it posed for a 30-minute image taken with my eVscope from San Francisco. Dim, mag 15.9 it is centered in the image. @unistellar.bsky.social
Last night it posed for a 30-minute image taken with my eVscope from San Francisco. Dim, mag 15.9 it is centered in the image. @unistellar.bsky.social
The asteroid is now known as 2025 UC11. This animation shows where the observations were made. #astronomy
October 30, 2025 at 10:12 PM
The asteroid is now known as 2025 UC11. This animation shows where the observations were made. #astronomy
A quick trip through the thermosphere turns newly-discovered asteroid ST25J47 from an Apollo to an Aten. It is no bigger than a meter.
October 30, 2025 at 9:58 PM
A quick trip through the thermosphere turns newly-discovered asteroid ST25J47 from an Apollo to an Aten. It is no bigger than a meter.
Reposted by Tony Dunn
After billions of years heading towards us, interstellar comet #3IATLAS is currently at its closest approach to the Sun right NOW. Perihelion. #astronomy #comet
October 29, 2025 at 4:46 AM
After billions of years heading towards us, interstellar comet #3IATLAS is currently at its closest approach to the Sun right NOW. Perihelion. #astronomy #comet
After billions of years heading towards us, interstellar comet #3IATLAS is currently at its closest approach to the Sun right NOW. Perihelion. #astronomy #comet
October 29, 2025 at 4:46 AM
After billions of years heading towards us, interstellar comet #3IATLAS is currently at its closest approach to the Sun right NOW. Perihelion. #astronomy #comet
Another mini-moon? Maybe. Newly discovered 2025 US6 is officially listed as an asteroid.
Unlike our quasi-moon 2025 PN7, this one is actually bound to Earth, for now.
Its orbit is pure chaos. Enjoy it while it lasts. It’ll probably be demoted to space junk.
Unlike our quasi-moon 2025 PN7, this one is actually bound to Earth, for now.
Its orbit is pure chaos. Enjoy it while it lasts. It’ll probably be demoted to space junk.
October 26, 2025 at 7:24 PM
Another mini-moon? Maybe. Newly discovered 2025 US6 is officially listed as an asteroid.
Unlike our quasi-moon 2025 PN7, this one is actually bound to Earth, for now.
Its orbit is pure chaos. Enjoy it while it lasts. It’ll probably be demoted to space junk.
Unlike our quasi-moon 2025 PN7, this one is actually bound to Earth, for now.
Its orbit is pure chaos. Enjoy it while it lasts. It’ll probably be demoted to space junk.
Some YouTubes, even one by a famous astrophysicist, confuse mini-moons with quasi-moons.
Simple test:
🔴 Delete the Sun.
– Still orbiting Earth, even years later? Mini-moon (bound), like 2024 PT5.
– Gone forever? Quasi-moon, like 2025 PN7.
Simple test:
🔴 Delete the Sun.
– Still orbiting Earth, even years later? Mini-moon (bound), like 2024 PT5.
– Gone forever? Quasi-moon, like 2025 PN7.
October 24, 2025 at 6:55 PM
Some YouTubes, even one by a famous astrophysicist, confuse mini-moons with quasi-moons.
Simple test:
🔴 Delete the Sun.
– Still orbiting Earth, even years later? Mini-moon (bound), like 2024 PT5.
– Gone forever? Quasi-moon, like 2025 PN7.
Simple test:
🔴 Delete the Sun.
– Still orbiting Earth, even years later? Mini-moon (bound), like 2024 PT5.
– Gone forever? Quasi-moon, like 2025 PN7.
What was 'quasi-moon' 2025 PN7 doing before it entered its quasi state? It was tracing horseshoe orbits. Horseshoe orbits are called that because some people think they look like horseshoes.
October 24, 2025 at 1:11 AM
What was 'quasi-moon' 2025 PN7 doing before it entered its quasi state? It was tracing horseshoe orbits. Horseshoe orbits are called that because some people think they look like horseshoes.
Watch Earth’s newest quasi-moon in motion. 🌍🌀
The new paper “Meet Arjuna 2025 PN7” confirms #asteroid 2025 PN7 is trapped in a quasi-satellite orbit, looping around Earth (in a rotating frame) from the 1960s to the 2080s.
iopscience.iop.org/article/10.3...
The new paper “Meet Arjuna 2025 PN7” confirms #asteroid 2025 PN7 is trapped in a quasi-satellite orbit, looping around Earth (in a rotating frame) from the 1960s to the 2080s.
iopscience.iop.org/article/10.3...
October 21, 2025 at 7:13 PM
Watch Earth’s newest quasi-moon in motion. 🌍🌀
The new paper “Meet Arjuna 2025 PN7” confirms #asteroid 2025 PN7 is trapped in a quasi-satellite orbit, looping around Earth (in a rotating frame) from the 1960s to the 2080s.
iopscience.iop.org/article/10.3...
The new paper “Meet Arjuna 2025 PN7” confirms #asteroid 2025 PN7 is trapped in a quasi-satellite orbit, looping around Earth (in a rotating frame) from the 1960s to the 2080s.
iopscience.iop.org/article/10.3...
Two Near-Earth Asteroids (NEAs) in the same field of view in my eVscope @unistellar. 2004 FN18 (middle) and 2000 EZ148.
October 18, 2025 at 8:32 PM
Two Near-Earth Asteroids (NEAs) in the same field of view in my eVscope @unistellar. 2004 FN18 (middle) and 2000 EZ148.
2 Near EarthAsteroids in 1 FOV? Last night I imaged 2000 EZ148 at mag 15.1, and 2004 FN18 at mag 15.6 from San Francisco with my eVscope. Tomorrow night (Friday around 11pm PDT), they will be of similar brightness as they pass only 0.33 degrees from each other. 2000 EZ148 is the left image.
October 17, 2025 at 5:16 AM
2 Near EarthAsteroids in 1 FOV? Last night I imaged 2000 EZ148 at mag 15.1, and 2004 FN18 at mag 15.6 from San Francisco with my eVscope. Tomorrow night (Friday around 11pm PDT), they will be of similar brightness as they pass only 0.33 degrees from each other. 2000 EZ148 is the left image.
What if Juno left Jupiter to get a closer look at interstellar comet 3I/ATLAS? With a couple of burns, Juno can get as close as 25 million km. Purely hypothetical, fun orbital mechanics! 🔭
Thanks @adamsspaceresearch.bsky.social for the research and trajectory data. @i4interstellar.bsky.social
Thanks @adamsspaceresearch.bsky.social for the research and trajectory data. @i4interstellar.bsky.social
October 11, 2025 at 1:39 AM
What if Juno left Jupiter to get a closer look at interstellar comet 3I/ATLAS? With a couple of burns, Juno can get as close as 25 million km. Purely hypothetical, fun orbital mechanics! 🔭
Thanks @adamsspaceresearch.bsky.social for the research and trajectory data. @i4interstellar.bsky.social
Thanks @adamsspaceresearch.bsky.social for the research and trajectory data. @i4interstellar.bsky.social
After last week's asteroid buzzed over Antarctica, the North Pole gets its turn. Newly-discovered #asteroid 2025 TQ2 (2-4 meters wide) passed 3,000 miles above the Fortress of Solitude. #Astronomy
October 5, 2025 at 9:43 PM
After last week's asteroid buzzed over Antarctica, the North Pole gets its turn. Newly-discovered #asteroid 2025 TQ2 (2-4 meters wide) passed 3,000 miles above the Fortress of Solitude. #Astronomy
Interstellar #comet 3I/ATLAS is hidden on the far side of the Sun from Earth. But today it sweeps past Mars, where orbiting spacecraft have ringside seats. Let’s hope they look up. #astronomy #NASA
October 2, 2025 at 10:37 PM
Interstellar #comet 3I/ATLAS is hidden on the far side of the Sun from Earth. But today it sweeps past Mars, where orbiting spacecraft have ringside seats. Let’s hope they look up. #astronomy #NASA
10 #asteroids passed closer than the Moon in a 5-day period from September 23-28. All were discovered this month. The largest up to 41 meters wide. #astronomy
September 30, 2025 at 9:48 PM
10 #asteroids passed closer than the Moon in a 5-day period from September 23-28. All were discovered this month. The largest up to 41 meters wide. #astronomy
October's comets. SWAN C/2025 R2, and Lemmon (C/2025 A6). Our interstellar visitor 3I/Atlas aka C/2025 N1, is unfortunately on the wrong side of the Sun for viewing, but I included it anyway because... well... it's interstellar. #Astronomy
September 27, 2025 at 4:53 AM
October's comets. SWAN C/2025 R2, and Lemmon (C/2025 A6). Our interstellar visitor 3I/Atlas aka C/2025 N1, is unfortunately on the wrong side of the Sun for viewing, but I included it anyway because... well... it's interstellar. #Astronomy
#Asteroid 2024 YR4 has a ~4 % chance of hitting the Moon on Dec 22 2032. A strike could spike micrometeoroid flux in low Earth orbit ~1000×, endangering satellites—so researchers even study nuclear disruption. arxiv.org/pdf/2509.12351
My sim: 2000 clones; 72 hit.
My sim: 2000 clones; 72 hit.
September 25, 2025 at 8:50 PM
#Asteroid 2024 YR4 has a ~4 % chance of hitting the Moon on Dec 22 2032. A strike could spike micrometeoroid flux in low Earth orbit ~1000×, endangering satellites—so researchers even study nuclear disruption. arxiv.org/pdf/2509.12351
My sim: 2000 clones; 72 hit.
My sim: 2000 clones; 72 hit.
#SanFrancisco Earthquake just now. Shaking started before the cell phone alert sounded.
September 22, 2025 at 9:57 AM
#SanFrancisco Earthquake just now. Shaking started before the cell phone alert sounded.
In the last 6 days, 9 asteroids passed inside the Moon’s orbit. Estimated sizes: ~1–38 m. All were discovered this month, a reminder that countless small, faint NEOs slip by unnoticed until they make a close pass.
September 21, 2025 at 6:35 AM
In the last 6 days, 9 asteroids passed inside the Moon’s orbit. Estimated sizes: ~1–38 m. All were discovered this month, a reminder that countless small, faint NEOs slip by unnoticed until they make a close pass.
It might seem scary that two mega-Chelyabinsks passed closer than the Moon this week. Good news: Earth is a small target. Even with gravitational lensing, our planet is only about 80% the size of a dartboard’s bullseye compared to the board itself. In fact, 2013 was the last time I had a bullseye.
September 21, 2025 at 3:55 AM
It might seem scary that two mega-Chelyabinsks passed closer than the Moon this week. Good news: Earth is a small target. Even with gravitational lensing, our planet is only about 80% the size of a dartboard’s bullseye compared to the board itself. In fact, 2013 was the last time I had a bullseye.
Reposted by Tony Dunn
El recientemente descubierto #asteroide #2025RJ2 pasará a solo 13.000 km de la #Luna. Cada vez el rastreo con los programas de seguimiento digitales son más efectivos. Vivimos una auténtica revolución como explico en:
theconversation.com/la-revolucio...
@planetarysociety.bsky.social
#PlanetSci 👇
theconversation.com/la-revolucio...
@planetarysociety.bsky.social
#PlanetSci 👇
Tomorrow, newly-discovered #asteroid 2025 RJ2 will miss the Moon by 13,000 km. Shortly before close approach, it will pass through the Moon's shadow.
September 16, 2025 at 8:27 AM
El recientemente descubierto #asteroide #2025RJ2 pasará a solo 13.000 km de la #Luna. Cada vez el rastreo con los programas de seguimiento digitales son más efectivos. Vivimos una auténtica revolución como explico en:
theconversation.com/la-revolucio...
@planetarysociety.bsky.social
#PlanetSci 👇
theconversation.com/la-revolucio...
@planetarysociety.bsky.social
#PlanetSci 👇
Tomorrow, newly-discovered #asteroid 2025 RJ2 will miss the Moon by 13,000 km. Shortly before close approach, it will pass through the Moon's shadow.
September 15, 2025 at 7:00 PM
Tomorrow, newly-discovered #asteroid 2025 RJ2 will miss the Moon by 13,000 km. Shortly before close approach, it will pass through the Moon's shadow.
A simulation of Earth's present and former quasi satellites as described in the Carlos de la Fuente Marcos and Raúl de la Fuente Marcos paper iopscience.iop.org/article/10.3... including newly-discovered 2025 PN7, first recognized as quasi by
@AdrienCoffinet
@AdrienCoffinet
September 14, 2025 at 2:02 AM
A simulation of Earth's present and former quasi satellites as described in the Carlos de la Fuente Marcos and Raúl de la Fuente Marcos paper iopscience.iop.org/article/10.3... including newly-discovered 2025 PN7, first recognized as quasi by
@AdrienCoffinet
@AdrienCoffinet