Image of Shoemaker-Levy 9 impacts on Jupiter by Hubble Space Telescope Comet Team and NASA.
You may not have been around or into astronomy when this happened, so here I'm posting my observing log entries from those special nights when black marks appeared in the cloud tops of Jupiter. It was an exciting event and I hope this gives you some sense of that, or brings back memories if you observed it yourself.
Comet Shoemaker-Levy 9 Impacts - Observing log entries
- Most observations were made with my Tasco 11TR 4.5 inch reflector from the parking lot of the apartment my brother, Paul, and I were sharing at the time in Bellevue, PA, on the north side of Pittsburgh (Bortle 8); some from our astronomy club's somewhat darker site in Freedom, PA, north of Pittsburgh.
- I lost the sketches somehow, but if I find them, I'll add them.
- At the time, I was using a scale for seeing (steadiness of the air) and transparency ("clarity") of 1 to 5, 1 being the best.
Seeing about 3/5 but wavy. Clarity not particularly good- some cirrus, a lot of haze, but Jupiter shining through fine. Quite a large festoon extending S off the NEB into the equatorial zone- one of the largest I've ever seen, just a little past the meridian. NEB is very wide, with the tiniest gap between it and the NTB. Much wider gap between the SEB and the STB. All four moons symmetrically lined up on the east side of Jupiter two by two, dipping down toward the center. 10:42 p.m. Seven minutes until predicted impact of fragment B. Image still undulating like Jello, but not blurring too much. Seeing variable.
10:48 p.m. One minute to predicted impact. Jupiter is about 5 degrees NE of the Moon tonight (a little past first quarter). Quite a bit of thin cloud cover in the area.
Seeing improved to 2/5.
11:11 p.m. Moon hazed over. The white spot on the STB of Jupiter about 4/5 of the way to the western limb now. Looking like this may be an event for big scopes above the atmosphere only. Nothing seen so far. B impact site should be coming around into view. Nothing. Jupiter dimming from clouds.
11:19 p.m. Clouds becoming a problem- very murky. Paul got home at 11:36. Conditions deteriorating. Lights in the parking lot don't help either.
11:48 p.m. Jupiter's image brightening a little, but the seeing is terrible. Gave up at 11:51, no impact effects visible.
July 18-19, 1994 (Mon. night) Bellevue, PA
(4.5-inch) First look at the Comet Shoemaker-Levy 9 impact effects. Incredible! Two dark spots on Jupiter's SW quadrant, very prominent. Some other mottling along the same latitude. Beyond what we expected (Paul and I) to be able to see. We can't believe the spots are this prominent! Easier than the Red Spot's ever been. The two spots were heading for the limb- did a sketch.
9:17 p.m. darkest spot nearing the limb.
Did a second sketch. A third spot is now just past the meridian. Fainter than the other two, but still well defined. However, nowhere near as dark as Ganymede's shadow on the N hemisphere (coming up on the meridian). We both noticed that the N polar area seems quite dark. A couple white spots on the STB, just N and E of the third impact spot.
11:30 p.m. We had moved out to the grocery store parking lot around the corner and had some people stop by to take a look - Tom, Dan, a woman and two little girls. No more impact spots came around the limb. We were hoping the big one, G, would appear, but we're losing Jupiter in the hazy murk now. Packed it in at 11:40 p.m.
July 19-20, 1994 (Tue. night) Bellevue, PA
(4.5-inch) Jupiter has two very big, very dark spots now in the impact zone. Amazingly large and dark- very prominent- most prominent features on Jupiter right now. We're still in twilight now. Clear but very hazy. Clarity only about 4/5.
Jupiter looks like a coconut with the two round dark spots on one end. Or maybe a bowling ball! The spots are definitely darker than the NEB or any other feature. The spot on the E side has an outer ring that's fainter than the inner area. The spots were so dark we could see them in Paul's little 60mm refractor with my 9mm eyepiece- fantastic! Tonight the spots are as dark as Ganymede's shadow was the other night, without sharply defined edges. Bob, from the astronomy club, is out at the [Freedom, PA] site tonight with some of the other guys (later reported the spots looked like two black eyes on Jupiter this night).
Seeing started out at about 4/5 and improved to 3/5. Jupiter a dark maize color due to the haze.
11:36 p.m. new spot coming around the E limb. First of the two dark spots going round the W limb.
10:55 p.m. packing it in- seeing worsened. The new spot is fainter and more diffuse than the other two big spots.
July 23-24, 1994 (Sat. night) Bellevue, PA
(4.5-inch) The last few nights all clouded up at sunset. Thought tonight might be different. Got a view of a big spot coming around Jupiter's limb- seeing very poor. Looks like there's a sprinkling of smaller spots along the zone, and they appear to be attenuating, forming more into a band. Started viewing at 9:10 p.m. The main spot is quite elongated, about the size of the Red Spot, but flatter and very dark- darker than any other feature on Jupiter. A large amount of activity on the S edge of the NEB, including one really big bump or festoon preceding the large impact spot in longitude. I'm continuing my series of sketches that I've done since the impacts started. A pronounced white spot visible on the STB. A little in front of the second spot visible (which is also elongated). May be my imagination, but there appears to be a dark band forming at the opposite latitude in the N hemisphere.
Clouds have pretty much stayed out of the way tonight.
Now it looks like there are actually two white spots close together on the STB.
Io is in shadow. Watched it reappear at 2203. Seeing improved for a while- best it's been since the comet impacts began. The darkest spot has a lighter center, with perhaps a detached portion more to the S. May even be a third white spot on the STB- smaller than the other two and following them around. The large impact spot now coming up on the meridian. Obviously more elongated now than three nights ago when these same three spots were visible. Almost cigar-shaped now, although a bit fatter. This is the same view as 7/18 (see sketches).
2155- Another spot came round the limb. Three teenage guys came by and took a quick look. I'm happy to report that Jupiter is rad.
Seems like the STB section just north of the darkest spot is correspondingly darker than the rest of the STB. Large festoon on the NEB makes it easy to identify this face of Jupiter. The darkest impact spot is slightly following (E) in longitude by 10 or 20 degrees.
Io reappearance from shadow was remarkably quick. It came up to full brightness in about a minute.
The Red Spot hasn't transited during any of my viewing times, so I don't know what it looks like now. I don't think I've seen it at all this viewing season.
2213- Another big impact spot "coming round the bend."
2251- Jupiter on the edge of a cloud bank. In and out of the clouds. Seeing deteriorated to about a 4 or 5. Call it 4.5. Two major spots still visible.
2315- Paul still not home from his temp job. Not much left to see with the clouds and altitude becoming a factor. Jupiter is only up about 20 degrees now. The second spot is a little larger than the first and not quite as elongated. Hard to see now. These spots are further apart than the ones on Tuesday night. The new one coming around the limb is massive.
2320- Seeing is 5. Jupiter rippling madly like it's in boiling water.
2338- Seeing improved a bit. Paul got home and got a halfway decent view. Another new spot is coming around the limb. Seeing worsened and we went in
July 25-26, 1994 (Mon. night) Bellevue, PA
(4.5-inch) Out looking at Jupiter again. Poor seeing=4. Started at 2225. At 2243 another large spot coming around the limb.
July 28-29, 1994 (Thu. night) Bellevue, PA
(4.5-inch) 2056 Continuing the "Jupiter Watch." Nice big spot approaching the meridian. Dim because the sky is very murky. Can make out the NEB, SEB, and the impact zone as a dark patch. Clarity=4.
2130 Still very dim through clouds. Gave up at 2139.
July 30-31, 1994 (Sat. night) Bellevue, PA
(4.5-inch) Seeing=2.5 to 3. Large sport coming around the limb followed by another fainter one, preceded by some straggly dark features in the impact belt. STB has darker segment past the meridian. A couple of bumps on the S side of the NEB.
Clouds came over Jupiter so I took a look at Albireo.
Jupiter came out again and I recognized the double-lobed spot as being the one from previous observations (7/23-24). Elongated more now, but not much. Hasn't changed much over the last week.
Seeing is very variable. NTB has gotten much less distinct lately- seems almost contiguous with the NEB now. Bright zone between the two doesn't seem to be as definite.
This major spot is the most interesting. Looks almost like there's a bright moon in front of it- a white "eye" in the middle, shifted up a little toward the S edge of the spot.
Packed it in at 2250.
July 31-Aug 1, 1994 (Sun. night) Bellevue, PA
(4.5-inch) Some of the larger spots visible. Possibly same view as on the night of 7/18-19. Spots are the darkest features on the planet, much more elongated now. Two major dark complexes visible now. Seeing=3 but very variable. Clarity=4. Viewed until 2207. Excellent view tonight!
Aug. 5-6, 1994 (Fri. night), Freedom, PA
(4.5-inch) A large elongated spot was just touching the W limb when I viewed it. Looked similar to the one I sketched on 8/1. Two moons were aligned N and S on the eastern side, presenting a nice overall effect.
Aug. 14-15, 1994 (Sun. night), Freedom, PA
(4.5-inch) Spots from comet impact still surprisingly dark; elongated but not forming a complete belt. Europa reappearing shortly.
Sep. 5-6, 1994 (Mon. night), Bellevue, PA
(4.5-inch) Quite a bit of dark spotting at the impact zone, still darker than the SEB. No individual spots visible due to smearing. Surprising how dark the impact site is, and the south polar cap also appears quite dark. Seeing very poor- scope has only been out in the air about 10 minutes, but Jupiter is setting lower. Looks like impact zone is a dark mottled belt, surprisingly dark- about same darkness as the NEB.
Composite of Hubble images showing the comet fragments approaching Jupiter. Stereogram created with Owl3D and Paint.net.
NASA, ESA, H. Weaver and E. Smith (STScI) and J. Trauger and R. Evans (NASA's Jet Propulsion Laboratory)
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