Marshall Eubanks
@marshall-eubanks.bsky.social
A physicist with a lead role in creating two Very Long Baseline Interferometry (VLBI) systems, for JPL & the USNO. Now Chief Scientist at Space Initiatives Inc, developing picospacecraft for use in deep space. Asteroid (6696) Eubanks is named in his honor.
C'est merveilleux.
November 22, 2025 at 2:14 PM
C'est merveilleux.
Keeping track of our interstellar visitor, 3I/ATLAS. Right now it is headed North and out of the solar system.
Amateur astronomers should take a look as it gets closer to Earth. Its closest approach to Earth will be on December 19 at a distance of 1.796 AU (269 million km, 168 million miles).
Amateur astronomers should take a look as it gets closer to Earth. Its closest approach to Earth will be on December 19 at a distance of 1.796 AU (269 million km, 168 million miles).
November 21, 2025 at 6:21 PM
Keeping track of our interstellar visitor, 3I/ATLAS. Right now it is headed North and out of the solar system.
Amateur astronomers should take a look as it gets closer to Earth. Its closest approach to Earth will be on December 19 at a distance of 1.796 AU (269 million km, 168 million miles).
Amateur astronomers should take a look as it gets closer to Earth. Its closest approach to Earth will be on December 19 at a distance of 1.796 AU (269 million km, 168 million miles).
A view of the solar system when Lucy observed 3I/ATLAS (and just after Psyche observed). These data will really help
- 3I orbit determination &
- determining the phase function (& thus the size) of the dust in the 3I coma.
(All pointed out here arxiv.org/abs/2508.15768 )
- 3I orbit determination &
- determining the phase function (& thus the size) of the dust in the 3I coma.
(All pointed out here arxiv.org/abs/2508.15768 )
November 20, 2025 at 11:56 AM
A view of the solar system when Lucy observed 3I/ATLAS (and just after Psyche observed). These data will really help
- 3I orbit determination &
- determining the phase function (& thus the size) of the dust in the 3I coma.
(All pointed out here arxiv.org/abs/2508.15768 )
- 3I orbit determination &
- determining the phase function (& thus the size) of the dust in the 3I coma.
(All pointed out here arxiv.org/abs/2508.15768 )
Annotated version of the first MRO HiRISE image of 3I/ATLAS from Mars orbit.
November 19, 2025 at 9:37 PM
Annotated version of the first MRO HiRISE image of 3I/ATLAS from Mars orbit.
It looks like 3I might get another CME around Nov. 23, just towards the end of the Juice observing period.
Hope it can see the tail wave!
Hope it can see the tail wave!
November 19, 2025 at 6:10 PM
It looks like 3I might get another CME around Nov. 23, just towards the end of the Juice observing period.
Hope it can see the tail wave!
Hope it can see the tail wave!
This image is the arrangement of the solar system at the time that picture was taken. 3I is moving to the right, so the dust tail (which lags behind the ion tail) will be displaced to the left. Juice imaging will have a rather different vantage point, allowing for 3-D mapping of the tail.
November 17, 2025 at 12:31 PM
This image is the arrangement of the solar system at the time that picture was taken. 3I is moving to the right, so the dust tail (which lags behind the ion tail) will be displaced to the left. Juice imaging will have a rather different vantage point, allowing for 3-D mapping of the tail.
It looks like our interstellar visitor 3I/ATLAS has finally gotten a dust tail. Very nice picture from
ICQ Comet Observations
Satoru Murata
2025-11-16 11:53:50~12:23:20 UTC
New Mexico, USA
ICQ Comet Observations
Satoru Murata
2025-11-16 11:53:50~12:23:20 UTC
New Mexico, USA
November 16, 2025 at 7:11 PM
It looks like our interstellar visitor 3I/ATLAS has finally gotten a dust tail. Very nice picture from
ICQ Comet Observations
Satoru Murata
2025-11-16 11:53:50~12:23:20 UTC
New Mexico, USA
ICQ Comet Observations
Satoru Murata
2025-11-16 11:53:50~12:23:20 UTC
New Mexico, USA
Alas, Dawn had to move on to Ceres and so we didn't get the best pictures from Dawn at the Vesta south pole, which is why we're relying on a Hubble data for this colorful elevation chart.
upload.wikimedia.org/wikipedia/co...
upload.wikimedia.org/wikipedia/co...
November 14, 2025 at 12:29 PM
Alas, Dawn had to move on to Ceres and so we didn't get the best pictures from Dawn at the Vesta south pole, which is why we're relying on a Hubble data for this colorful elevation chart.
upload.wikimedia.org/wikipedia/co...
upload.wikimedia.org/wikipedia/co...
I am neither a geologist nor a stone tool maker, so I wouldn't know.
I know from attending talks that the resulting crater - Rheasilvia - is huge, and Vesta was / is solid enough (i.e., small enough) that the body left it more or less as it was.
upload.wikimedia.org/wikipedia/co...
I know from attending talks that the resulting crater - Rheasilvia - is huge, and Vesta was / is solid enough (i.e., small enough) that the body left it more or less as it was.
upload.wikimedia.org/wikipedia/co...
November 14, 2025 at 12:27 PM
I am neither a geologist nor a stone tool maker, so I wouldn't know.
I know from attending talks that the resulting crater - Rheasilvia - is huge, and Vesta was / is solid enough (i.e., small enough) that the body left it more or less as it was.
upload.wikimedia.org/wikipedia/co...
I know from attending talks that the resulting crater - Rheasilvia - is huge, and Vesta was / is solid enough (i.e., small enough) that the body left it more or less as it was.
upload.wikimedia.org/wikipedia/co...
You could do it Vesta - in fact, nature did. Took out a big chunk of its South pole - you can buy pieces (HED meteorites) for a few $100.
That was a real knapping.
That was a real knapping.
November 14, 2025 at 1:24 AM
You could do it Vesta - in fact, nature did. Took out a big chunk of its South pole - you can buy pieces (HED meteorites) for a few $100.
That was a real knapping.
That was a real knapping.
The inner solar system today, Nov. 12, 2025, as our interstellar visitor, 3I/ATLAS, continues to race past. It has survived perihelion (its closest approach to the Sun) & is now under observation by the Juice spacecraft - also, the Earth is starting to get a good view as well.
November 12, 2025 at 12:23 PM
The inner solar system today, Nov. 12, 2025, as our interstellar visitor, 3I/ATLAS, continues to race past. It has survived perihelion (its closest approach to the Sun) & is now under observation by the Juice spacecraft - also, the Earth is starting to get a good view as well.
Interstellar comet 3I/ATLAS (aka C/2025 N1 ATLAS): the ion tail is getting longer – 11 Nov. 2025.
by Gianluca Masi and the Virtual telescope
Our interstellar visitor is really putting on a show for Juice, which is collecting data now.
by Gianluca Masi and the Virtual telescope
Our interstellar visitor is really putting on a show for Juice, which is collecting data now.
November 11, 2025 at 1:57 PM
Interstellar comet 3I/ATLAS (aka C/2025 N1 ATLAS): the ion tail is getting longer – 11 Nov. 2025.
by Gianluca Masi and the Virtual telescope
Our interstellar visitor is really putting on a show for Juice, which is collecting data now.
by Gianluca Masi and the Virtual telescope
Our interstellar visitor is really putting on a show for Juice, which is collecting data now.
We have received more PUNCH data on our interstellar visitor, 3I/ATLAS. There seems to have been oscillations in brightness right around perihelion, but I think it is getting slowly dimmer now.
November 11, 2025 at 5:21 AM
We have received more PUNCH data on our interstellar visitor, 3I/ATLAS. There seems to have been oscillations in brightness right around perihelion, but I think it is getting slowly dimmer now.
And, unlike many past comets, we have been keeping a very close eye on 3I, including completely through perihelion, with a large combination of interplanetary and Earth orbiting spacecraft. We _know_ it hasn't been misbehaving.
November 11, 2025 at 2:54 AM
And, unlike many past comets, we have been keeping a very close eye on 3I, including completely through perihelion, with a large combination of interplanetary and Earth orbiting spacecraft. We _know_ it hasn't been misbehaving.
There are more PUNCH (orbital) and COBS (ground based) magnitude data for our interstellar visitor, 3I / ATLAS. It is a little too soon to say its brightness is declining as expected, but I think that (as expected) it has clearly stopped its pre-perihelion brightening trend.
November 10, 2025 at 1:44 PM
There are more PUNCH (orbital) and COBS (ground based) magnitude data for our interstellar visitor, 3I / ATLAS. It is a little too soon to say its brightness is declining as expected, but I think that (as expected) it has clearly stopped its pre-perihelion brightening trend.
Image of our interstellar visitor 3I/ATLAS from the Chinese TianWen-1 Mars orbiter back in September (plus the usual plethora of cosmic ray hits on raw space images)
www.cnsa.gov.cn/n6758823/n67...
www.cnsa.gov.cn/n6758823/n67...
November 6, 2025 at 12:45 PM
Image of our interstellar visitor 3I/ATLAS from the Chinese TianWen-1 Mars orbiter back in September (plus the usual plethora of cosmic ray hits on raw space images)
www.cnsa.gov.cn/n6758823/n67...
www.cnsa.gov.cn/n6758823/n67...
Post perihelion optical data on our interstellar visitor, 3I/ATLAS.
- the G band optical data seems to be about 1.7 magnitudes high (i.e., fainter) than PUNCH since early September.
- my model is about 0.6 magnitudes lower (i.e., brighter) than either PUNCH and LASCO C3
- the G band optical data seems to be about 1.7 magnitudes high (i.e., fainter) than PUNCH since early September.
- my model is about 0.6 magnitudes lower (i.e., brighter) than either PUNCH and LASCO C3
November 5, 2025 at 8:55 PM
Post perihelion optical data on our interstellar visitor, 3I/ATLAS.
- the G band optical data seems to be about 1.7 magnitudes high (i.e., fainter) than PUNCH since early September.
- my model is about 0.6 magnitudes lower (i.e., brighter) than either PUNCH and LASCO C3
- the G band optical data seems to be about 1.7 magnitudes high (i.e., fainter) than PUNCH since early September.
- my model is about 0.6 magnitudes lower (i.e., brighter) than either PUNCH and LASCO C3
A new R band magnitude from today for our interstellar visitor, 3I/ATLAS. Note that we expect these "red" magnitudes to be below the wide band magnitudes including the green gas coma.
We can expect 3I to decline in brightness now - the question is, how fast?
We can expect 3I to decline in brightness now - the question is, how fast?
November 3, 2025 at 1:17 PM
A new R band magnitude from today for our interstellar visitor, 3I/ATLAS. Note that we expect these "red" magnitudes to be below the wide band magnitudes including the green gas coma.
We can expect 3I to decline in brightness now - the question is, how fast?
We can expect 3I to decline in brightness now - the question is, how fast?
I added the new ground based Lowell (G37) post-perihelion magnitude measurement (r' band) to the MPC R and r data. It's a bit higher as I would expect.
November 1, 2025 at 1:27 AM
I added the new ground based Lowell (G37) post-perihelion magnitude measurement (r' band) to the MPC R and r data. It's a bit higher as I would expect.
Now we're up to perihelion and, yes, 3I/ATLAS is behaving itself.
October 31, 2025 at 4:41 PM
Now we're up to perihelion and, yes, 3I/ATLAS is behaving itself.
We now have roughly complete magnitude data for our interstellar visitor 3I / ATLAS, up to its perihelion
This includes SOHO LASCO and GOES-19 CCOR-1 data from arxiv.org/abs/2510.25035
This plot looks pretty good to me. My congratulations to all those who worked so hard on this.
This includes SOHO LASCO and GOES-19 CCOR-1 data from arxiv.org/abs/2510.25035
This plot looks pretty good to me. My congratulations to all those who worked so hard on this.
October 31, 2025 at 5:26 AM
We now have roughly complete magnitude data for our interstellar visitor 3I / ATLAS, up to its perihelion
This includes SOHO LASCO and GOES-19 CCOR-1 data from arxiv.org/abs/2510.25035
This plot looks pretty good to me. My congratulations to all those who worked so hard on this.
This includes SOHO LASCO and GOES-19 CCOR-1 data from arxiv.org/abs/2510.25035
This plot looks pretty good to me. My congratulations to all those who worked so hard on this.
Thanks to Kevin Walsh at SWRI, we now have a data point from the day of the perihelion of our interstellar visitor 3I/ATLAS!
It seems to be behaving itself.
It seems to be behaving itself.
October 30, 2025 at 5:16 PM
Thanks to Kevin Walsh at SWRI, we now have a data point from the day of the perihelion of our interstellar visitor 3I/ATLAS!
It seems to be behaving itself.
It seems to be behaving itself.
And with the new data
October 30, 2025 at 1:40 AM
And with the new data
Now October 27th
October 30, 2025 at 1:31 AM
Now October 27th
An updated magnitude plot for our Interstellar visitor 3/ATLAS including WFI PUNCH data for October 27, the first data point _after_ 3I's superior conjunction with Earth.
It's a little below the prediction, but that's OK.
It's a little below the prediction, but that's OK.
October 30, 2025 at 1:28 AM
An updated magnitude plot for our Interstellar visitor 3/ATLAS including WFI PUNCH data for October 27, the first data point _after_ 3I's superior conjunction with Earth.
It's a little below the prediction, but that's OK.
It's a little below the prediction, but that's OK.