Report by The Lunascan Project
Ridge) & VGL (Lan Fleming)
One of over 400
of object apparently
orbiting the Moon.
Frontiers of Science/ papers/ridge/v01n02b.pdf
Date: September 21, 1996
- Session #: 24
- Lunar range: 228,722 miles, 95.75% of mean
- Age: 9.5 days of 29.53 day cycle
- Phase: 68.9% waxing
- Orientation: Northern hemisphere up, normal
- Sky conditions: Clear with a little haze, lunar halo.
- 7:26 PM local time, 00H26m CUT.
During routine scans of the lunar surface with the 16"
with a CCD camera, The Lunascan Project team tracked an unknown object
near the SE lunar limb for twenty seconds. The Moon was under HPS Mode
(High-Power Scanning) at 400 power, putting the surface at less than
miles. The scope/camera system had been in manual control to the limb,
then used the Earth's rotation to slowly scan to the terminator. Once
the darkness of the lunar night the system was manually pulled back to
the limb for another scan, each slice slightly different.
At the BOS (Beginning Of Session, 7:00 PM) the numbers for
had been routinely punched into the DOB Driver II computer. However,
the auto-track mode causes short L-shaped jerky movements during
the computer is placed in Pan which is manual. As team members watched
the outside monitor, they noticed in the blackness of space to the
of the Moon, a very brief bright speck. Due to deterioration of the
the session was terminated at 10:00 PM and the datatapes rewound.
At 00H26m CUT, queued on the tape, was the object. At first
it looked somewhat like a satellite of Jupiter. In fact, the object was
about that size. But no star, let alone any moon of Jupiter, had ever
the glare of the lunar limb. Not once during the last year and 23 other
sessions had the scope picked up anything that close. Immediately the
main computer was booted up and EZ Cosmos was loaded. The status screen
read the current date and time. The exact time of the incident was
in and the sky chart was put onscreen. Upon zooming in on the Moon and
sky sector, to see if there was a bright star or planet nearby that
account for the object, it was determined that nothing conspicuous was
anywhere near the Moon. Before the end of the hour a frame-grabbed
had been placed on The Lunascan Project web site. By Monday afternoon a
complete report was filed.
- Analysis shows shows target acquisition for less than a
of target for around six seconds, re-acquistion and recording for 13
before the scope/cam panned by Earth rotation let the object leave the
FOV at upper right. Almost 400 frames.
- The FOV at HPS 400 was 306 miles wide by 241 miles.
- Total time of observation was was 20 seconds.
- The coordinates of the unknown were about: RA 19'.008
Dec -19 degrees
18' 00 Alt 32.00 Azm 172.00
- Further checks with the brightness control turned up
showed the lunar
surface features tracking with the object. Therefore the object's
motion was zero.
- The object's apparent distance from the lunar limb was
less than the apparent diameter of the planet Jupiter.
- The object's size calculates out to be comparable to
that of Ganymede
and measures about 2 mm on the monitor, or a little over 2.375 miles in
diameter at lunar range. With the help of numerous consultants the
was determined: In general, the FOV is so restricted that SOME relative
motion should have been noticeable for just about everything.
- Low Earth Orbit (LEO) satellite eliminated. Object's
speed is much too slow. The orbital period of LEO satellites are
80 minutes, which is a geocentric angular velocity of 360 degrees every
1.5 hours or 0.075 degrees per second. In the 20 seconds the object was
observed, it should have moved about 1.5 degrees or three lunar
(the angular diameter of the moon as observed from the Earth is 1/2
- Geosynchronous satellite. A GSS would move .004 degrees
per second relative
to the fixed stars (360 degrees in 24 hours). In 20 seconds, it would
0.08 degrees, which is larger than the FOV. If the object were a
satellite, the movement should be easily noticeable because the object
would move out of the FOV entirely in 20 seconds.
- Object cannot be a star or planet. No star or planet has
ever been videotaped
during any of the previous 23 sessions due to the lunar glare. However,
the moon's monthly orbital period would cause the moon to move away
a fixed star or planet at a rate of .00015 degrees per second,
IF it were possible to record such an event.
- Balloon. Potentially motionless, a balloon drifting with
the air currents
at a leisurely 10mph 100 miles away would still move .03 degrees in 20
seconds, or half the FOV. Since the telescope was elevated 32 degrees
the horizontal, that would also put this hypothetical balloon at an
of about 50 miles.
- Meteor. The lunar escape velocity of 5400mph is the
at which a meteoroid can approach the moon. That is 1.5 times the
lunar orbital velocity of 3400, and it is almost 10% of your FOV. The
of objects in the solar system would approach the moon at much greater
Trajectories could be envisioned that could make such an
stationary relative to the moon for 20 seconds to an Earth-based
but the data now appears to be more in favor of an object in lunar
A maximum speed of about 3400mph for something in lunar orbit
into an angular velocity as viewed from Earth of .0002 degrees per
In the 20 second time span in which the object was in view, that would
produce an angular displacement relative to the moon of only .004
or about 6% of the .06 degree FOV. But this is only for objects
near the surface of the moon. The speed decreases rapidly with
which would make the motion increasingly difficult to detect. As for
meteoroids, trajectories could again be envisioned that would hide the
true motion of the object in the lunar reference frame from an
observer. But the set of possible paths that would do this is going to
be larger for a slow-moving orbiter than for a faster-moving
This seems to favor the interpretation of the object as being a lunar
It is also unlikely that astronomers would miss a 2-mile long asteroid
that got this close to Earth!
- Asteroid. If this were an asteroid there should have
been some movement.
JPL says something like 8-arcsec in 20-sec time-exposure is not
And we're not assuming an asteroid as a natural lunar orbiter. That
be nearly impossible.
- Object in lunar orbit. Mascons prevent anything from
orbiting very long
without corrections. If it's in orbit, it is highly reflective,
much smaller than it appears, and man-made.
- Internal reflection. Cam/scope bounce at beginning of
track shows object
and Moon in-sync, similar to motion you'd get from observing Jupiter
it's moons. This is not a reflection of any kind.
The lack of apparent motion relative to the moon could be
explained by an orbiter. While the low-altitude orbital speed at the
is such that an object would move a maximum distance of 5% of the
FOV in the 20-second observation time, there are two points in a lunar
orbit at which the object would appear to be motionless relative to the
moon as observed from Earth: the point in the orbit where the object is
moving directly toward the Earth and the point where it is moving
away. The two points would be close to the positions where the object
farthest from the moon's limb and are the only places where the object
would likely be seen at all. Assuming the object was at the apparent
altitude above the moon in the video image and had a two-hour orbital
there would only be a period of 11 minutes between when the object
from behind the moon and when it moved across the moon's disk where it
would be lost in the direct moon light. Within that 11-minute time
the object might be visible for only a few seconds at its farthest
from the moon's limb before it became lost in the bright moonlight
though the Earth's atmosphere close to the limb. (The image that
has on his web site shows this atmospheric haze around the moon.) Such
an object might therefore appear suddenly and disappear just as
after the 20-second period that Mr. Ridge observed the object. That
make an object orbiting the moon a more likely explanation than an
travelling straight toward Earth. The only problem with the orbiter
is that the chances of the moon capturing an asteroid seem to be close
to nil. It's low gravitation would make captures rare, and the orbit
quickly degrade due to the the gravitional anomalies associated with
The estimate I've heard is that any orbiting object will either escape
the moon or impact it within about a year.
"There are two points in a lunar
orbit at which the object
would appear to be motionless relative to the moon as observed from
the point in the orbit where the object is moving directly toward the
and the point where it is moving directly away. The two points would be
close to the positions where the object was farthest from the moon's
and are the only places where the object would likely be seen at all."
should have qualified that a bit. This would only apply for an object
a lunar orbit if the orbital plane were perpendicular to the the plane
of the telescope field of view. If the orbital plane were instead
to the FOV plane, the object would appear to be circling the moon at
constant altitude and speed. The orbital plane would probably be
between the two extremes. However, most asteroids travel in the
plane, so if one happened to get captured by the moon, its orbital
would be in the ecliptic. Since the ecliptic is very nearly
to the plane of a telescope FOV, the orbiting object would appear
motionless from Earth at its maximum distance from the moon's limb. A
possibility might be some tank on some probe venting for some reason.
resulting gas cloud could be visible from Earth before it disappeared
a matter of seconds. And, in fact, the report reminds me the cloud
saw when Apollo 13's tank gave way -- a spot of light that was gone
in seconds. (That one was easily visible to the naked eye, I think I
... but it was 100,000 miles away, not 250,000 miles.)
One-hour video documentary with report and footage on
available. Shipped Priority Mail. Send money order for $23 to:
The Lunascan Project
618 Davis Drive
Mt. Vernon, IN 47620