# First Interstellar Asteroid Spotted

#### Nicholas Kang

##### Tutorial Publisher
Tutorial Publisher
News Reporter

Last week, astronomers using the PanSTARRS 1 telescope perched on the Haleakalā volcano on the island of Maui spotted what they believe is the first comet (now recategorized as asteroid) ever detected that does not orbit the sun.

The comet, designated C/2017 U1, appears to have come from the direction of the constellation Lyra, and preliminary observations indicate it has a higher eccentricity than any known comet (1.1815), suggesting it is on a hyperbolic interstellar trajectory. The team's observations were published today by the International Astronomical Union's Minor Planet Center

Comet C/2017 U1 came in almost perpendicular to the orbital plane of the solar system and flew right under our noses, only 15,000,000 miles (24,000,000 km) from Earth, about half the distance to Mars. It is the highly eccentric orbit of the comet, meaning the orbit deviates significantly from a circle, that leads astronomers to believe it came from beyond the solar system.

Comet PanSTARRS (C/2017 U1) raced within about 0.25 astronomical unit of the Sun in early September and is now relatively close to Earth. Based on its extreme orbit, astronomers believe it arrived here from interstellar space. NASA / JPL / Horizons

Here's how Comet PanSTARRS (C/2017 U1) looked on October 21st as recorded at Tenagra Observatory near Rio Rico, Arizona. The images span 9 minutes, during which time the telescope tracked the object's motion, so background stars appear trailed. Each field is 3 arcminutes wide with north up. Paulo Holvorcem & Michael Schwartz (NASA grant #NNX15AE89G)

Code:
M.P.E.C. 2017-U181                               Issued 2017 Oct. 25, 03:53 UT

The Minor Planet Electronic Circulars contain information on unusual
minor planets and routine data on comets.  They are published
on behalf of Division F of the International Astronomical Union by the
Minor Planet Center, Smithsonian Astrophysical Observatory,
Cambridge, MA 02138, U.S.A.

Prepared using the Tamkin Foundation Computer Network

[email protected]
URL http://www.minorplanetcenter.net/    ISSN 1523-6714

COMET C/2017 U1 (PANSTARRS)

Further observations of this object are very much desired.  Unless there
are serious problems with much of the astrometry listed below, strongly
hyperbolic orbits are the only viable solutions.  Although it is probably
not too sensible to compute meaningful original and future barycentric orbits,
given the very short arc of observations, the orbit below has e ~ 1.2 for
both values.  If further observations confirm the unusual nature of this
orbit, this object may be the first clear case of an interstellar comet.

Observations:
CK17U010  C2017 10 18.47298 01 59 57.442+02 06 04.30         19.8 TLEU181F51
CK17U010  C2017 10 18.49990 01 59 08.910+02 07 20.19               LEU181F51
CK17U010  C2017 10 19.39715 01 34 55.362+02 45 03.20         19.9 TLEU181F51
CK17U010  C2017 10 19.40837 01 34 38.745+02 45 28.24         19.9 TLEU181F51
CK17U010  C2017 10 19.41968 01 34 21.948+02 45 53.55         20.1 TLEU181F51
CK17U010  C2017 10 19.43106 01 34 05.174+02 46 18.89         20.1 TLEU181F51
CK17U010 KC2017 10 19.86072 01 24 07.89 +03 01 07.5          19.6 TUEU181104
CK17U010 KC2017 10 19.86492 01 24 02.21 +03 01 16.3          19.8 TUEU181104
CK17U010 KC2017 10 19.86905 01 23 56.69 +03 01 24.7          20.3 TUEU181104
CK17U010 KC2017 10 19.94093401 22 22.288+03 03 53.76         20.3 TUEU181J04
CK17U010 KC2017 10 19.94390101 22 18.372+03 03 59.57         20.1 TUEU181J04
CK17U010  C2017 10 20.17250 01 17 27.47 +03 11 07.8          19.9 TUEU181I52
CK17U010  C2017 10 20.17348 01 17 26.22 +03 11 09.6          20.2 TUEU181I52
CK17U010  C2017 10 20.17448 01 17 24.96 +03 11 11.3          20.2 TUEU181I52
CK17U010  C2017 10 20.17546 01 17 23.73 +03 11 13.0          20.6 TUEU181I52
CK17U010 KC2017 10 21.22371 00 57 56.30 +03 39 16.9          20.2 ToEU181291
CK17U010 KC2017 10 21.22623 00 57 53.76 +03 39 20.5          19.5 ToEU181291
CK17U010 KC2017 10 21.22877 00 57 51.19 +03 39 24.2          19.6 ToEU181291
CK17U010  C2017 10 21.37476 00 55 26.71 +03 42 45.0          20.4 ToEU181926
CK17U010  C2017 10 21.37804 00 55 23.53 +03 42 49.8          20.1 ToEU181926
CK17U010  C2017 10 21.38132 00 55 20.35 +03 42 53.7          20.4 ToEU181926
CK17U010 |C2017 10 22.29708 00 41 56.27 +04 01 25.0                vEU181H06
CK17U010 |C2017 10 22.30118 00 41 52.93 +04 01 29.3                vEU181H06
CK17U010 |C2017 10 22.30512 00 41 49.76 +04 01 33.5          20.7 TvEU181H06
CK17U010 1C2017 10 22.46548 00 39 44.84 +04 04 55.4                 EU181Q62
CK17U010 1C2017 10 22.47027 00 39 41.16 +04 04 59.9                 EU181Q62
CK17U010 1C2017 10 22.47506 00 39 37.39 +04 05 04.8          19.9 T EU181Q62
CK17U010 KC2017 10 23.18830 00 31 01.55 +04 16 02.6          20.4 TqEU181734
CK17U010 KC2017 10 23.19547 00 30 56.65 +04 16 08.7          20.1 TqEU181734
CK17U010 KC2017 10 23.20264 00 30 51.76 +04 16 14.6          20.4 TqEU181734
CK17U010  C2017 10 24.23395 00 20 19.64 +04 30 08.4          20.9 TUEU181G96
CK17U010  C2017 10 24.23917 00 20 16.75 +04 30 12.3                UEU181G96
CK17U010  C2017 10 24.24438 00 20 13.82 +04 30 15.6          21.0 TUEU181G96
CK17U010  C2017 10 24.24957 00 20 10.85 +04 30 19.7          20.7 TUEU181G96

Observer details:
104 San Marcello Pistoiese.  Observers P. Bacci, M. Maestripieri.  Measurers
P. Bacci, L. Tesi, G. Fagioli.  0.60-m f/4 reflector + CCD.
291 LPL/Spacewatch II.  Observer R. A. Mastaler.  1.8-m f/2.7 reflector + CCD.
734 Farpoint Observatory.  Observer G. Hug.  0.69-m reflector + CCD.
926 Tenagra II Observatory.  Observers M. Schwartz, P. R. Holvorcem.  Measurer
M. Schwartz.  0.81-m f/7 Ritchey-Chretien + CCD.
F51 Pan-STARRS 1, Haleakala.  Observers J. Bulger, T. Lowe, A. Schultz,
M. Willman.  Measurers K. Chambers, S. Chastel, L. Denneau, H. Flewelling,
M. Huber, E. Lilly, E. Magnier, R. Wainscoat, C. Waters, R. Weryk.  1.8-m
Ritchey-Chretien + CCD.
G96 Mt. Lemmon Survey.  Observer G. J. Leonard.  Measurers E. J. Christensen,
D. C. Fuls, A. R. Gibbs, A. D. Grauer, J. A. Johnson, R. A. Kowalski,
S. M. Larson, G. J. Leonard, R. G. Matheny, R. L. Seaman, F. C. Shelly.
1.5-m reflector + 10K CCD.
H06 iTelescope Observatory, Mayhill.  Observer H. Sato.  0.43-m f/6.8
astrograph + CCD + f/4.5 focal reducer.
I52 Steward Observatory, Mt. Lemmon Station.  Observer R. A. Kowalski.
Measurers E. J. Christensen, D. C. Fuls, A. R. Gibbs, A. D. Grauer,
J. A. Johnson, R. A. Kowalski, S. M. Larson, G. J. Leonard, R. G. Matheny,
R. L. Seaman, F. C. Shelly.  1.0-m reflector + CCD.
J04 ESA Optical Ground Station, Tenerife.  Observer D. Abreu.  Measurers
M. Micheli, D. Koschny, M. Busch, A. Knoefel, E. Schwab.  1.0-m f/4.4
reflector + CCD.
Q62 iTelescope Observatory, Siding Spring.  Observer H. Sato.  0.51-m f/6.8
astrograph + CCD + f/4.5 focal reducer.

Orbital elements:
C/2017 U1 (PANSTARRS)
Epoch 2017 Sept. 4.0 TT = JDT 2458000.5
T 2017 Sept.  9.41719 TT                                MPCW
q   0.2515404            (2000.0)            P               Q
z  -0.7541603      Peri.  241.01670     -0.63536548     +0.68733697
+/-0.0181483      Node    24.61531     +0.49903801     +0.71329677
e   1.1897018      Incl.  122.32770     -0.58929769     -0.13702411
From 34 observations 2017 Oct. 18-24, mean residual 0".5.

Ephemeris:
C/2017 U1 (PANSTARRS)
Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase   m1    m2
2017 09 25    09 48 43.3 -06 12 59   0.6925  0.5884    34.9   102.8  20.5
...
2017 10 10    07 36 11.4 -05 42 56   0.2294  0.9879    80.7    86.0  18.8
...
2017 10 18    02 14 50.4 +01 42 29   0.1968  1.1887   166.6    11.2  18.7
...
2017 10 24    00 22 33.4 +04 27 26   0.3622  1.3344   156.3    17.4  20.2
2017 10 25    00 13 40.3 +04 38 57   0.3943  1.3583   153.3    19.2  20.4
2017 10 26    00 06 10.5 +04 48 35   0.4270  1.3821   150.6    20.7  20.6
...
2017 11 01    23 38 46.8 +05 25 33   0.6318  1.5233   138.3    25.7  21.6
...
2017 11 09    23 23 45.8 +05 54 48   0.9168  1.7069   127.0    27.6  22.5
...
2017 11 24    23 16 52.8 +06 41 38   1.4693  2.0399   110.7    26.9  23.8

Gareth V. Williams           (C) Copyright 2017 MPC           M.P.E.C. 2017-U181

Source:

Space.com
Popular Mechanics
IAU Minor Planet Center
Universe Today
Sky and Telescope

Last edited:

Ramans!

#### Urwumpe

##### Not funny anymore
Donator
Downgraded to asteroid it seems, but still clearly interstellar at 1.2 eccentricity.

#### boogabooga

##### Bug Crusher
My initial instinct on seeing this was skepticism that something interstellar would have come this close to the sun. And since velocities are so low in Oort cloud, it is possible for collisions, etc. to put comets on hyperbolic trajectories. But, if you run the numbers, e= 1.2 at 0.25 AU perihelion gives V infinity of about 25,500 m/s, and nothing in Oort Cloud is moving that fast, or could be reasonably expected to accelerate to that speed.

The universe must be crawling with comets. :blink:

#### N_Molson

Donator
Happy that one missed us, way too fast to even see it coming. We really live on luck when it comes to this. :shifty:

#### statickid

##### CatDog from Deimos
Donator
Luck and really really super duper low low low low probability :lol:

#### boogabooga

##### Bug Crusher
Part of me wonders if we just got....visited.

:hide:

#### Urwumpe

##### Not funny anymore
Donator
Part of me wonders if we just got....visited.

:hide:

You mean a Phoebe virus probe? :lol:

#### N_Molson

Donator
Part of me wonders if we just got....visited.

Lets say it makes the theory of panspermia very interesting, for sure. If there is any kind of carrier between stellar systems... Its not like every object went through a white room prior its journey (and even that isn't a guarantee of totally perfect sterility) :hmm:

#### Linguofreak

##### Well-known member
My initial instinct on seeing this was skepticism that something interstellar would have come this close to the sun. And since velocities are so low in Oort cloud, it is possible for collisions, etc. to put comets on hyperbolic trajectories. But, if you run the numbers, e= 1.2 at 0.25 AU perihelion gives V infinity of about 25,500 m/s, and nothing in Oort Cloud is moving that fast, or could be reasonably expected to accelerate to that speed.

The universe must be crawling with comets. :blink:

Current models indicate that 90-99% of comets are ejected from their systems of formation.

#### Andy44

##### owner: Oil Creek Astronautix
Luck and really really super duper low low low low probability :lol:

Luck and probability are functionally the same thing...low probability of collision = high level of luck.

---------- Post added at 12:37 AM ---------- Previous post was at 12:35 AM ----------

As for being "visited", all I can say is, "Do you want the Andromeda Strain? Because that's how you get the Andromeda Strain!

#### Kyle

##### Armchair Astronaut
Part of me wonders if we just got....visited.

:hide:

We can expect two more. The Ramans do everything in threes.

#### boogabooga

##### Bug Crusher
Current models indicate that 90-99% of comets are ejected from their systems of formation.

Serious question that I will not take the time to calculate for myself:

Assume all "stars" are spheres of 0.25 AU diameter.

What is the total angle of all the space occupied by all "stars" within say, 100 LY from the Sun?

In other words, what total percentage of the 'area' of the night sky is occupied by actual stars?

Last edited:

#### Notebook

News Reporter
Donator
http://www.bbc.co.uk/news/science-environment-42019778

The first known asteroid to visit our Solar System from interstellar space has been given a name.
Scientists who have studied its speed and trajectory believe it originated in a planetary system around another star.
The interstellar interloper will now be referred to as 'Oumuamua, which means "a messenger from afar arriving first" in Hawaiian.
The name reflects the object's discovery by a Hawaii-based astronomer using an observatory on Maui.

#### boogabooga

##### Bug Crusher
Why name it when nobody will ever see it again?

#### Artlav

##### Aperiodic traveller
Beta Tester
If nobody will ever see it again, then mankind must have failed as a species some time in the near future.

It's still there, it's trajectory known, and given even mildly futuristic tech it can be reached.

#### boogabooga

##### Bug Crusher
I disagree.

It's going to be long gone, and very difficult to ever find again. It's trajectory is only somewhat known; there is always uncertainty in the measurement.

Also, from what I understand now, this sort of thing should be a roughly yearly occurrence, given the number of rogue comets out there. It will be easier for "mildly futuristic tech" to just go after another one that comes along.

#### Linguofreak

##### Well-known member
Part of me wonders if we just got....visited.

:hide:

When I first saw this I sorta rolled my eyes, but actually, given the lack of a coma, I think that it's actually a real, though *very* remote possibility. A probe would be one sort of object that we would expect to come from interstellar space and not show a coma.

#### boogabooga

##### Bug Crusher
At the time that I wrote that, I was unaware how common this occurrence should be. I've since seen an estimate that this should be a yearly occurrence, rather than a once in a millennium occurrence. I've since forgotten the source, though.

#### Linguofreak

##### Well-known member
At the time that I wrote that, I was unaware how common this occurrence should be. I've since seen an estimate that this should be a yearly occurrence, rather than a once in a millennium occurrence. I've since forgotten the source, though.

Again, I don't think it's an at all *likely* possibility, but the lack of a coma makes it a possibility, even though it's pretty much the first thing we shave away with Occam's Razor.

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