Archive for the ‘Planet’ Category


Observing report: the transit of Mercury from western Colorado

May 19, 2016

Mercury transit 9 May 2016 - telescope setup

I was in Utah from May 4 to May 15, chasing dinosaurs with Mike Taylor, a colleague of mine from England. I took a telescope along in hopes of getting some dark-sky time, and to hopefully catch the transit of Mercury on May 9.

Things did not look promising at dawn on the 9th. I was in Fruita, Colorado, and when I got out of bed, the sky was completely overcast. Mike and I decided to head out west of town to visit Rabbit Valley, where a nearly complete skeleton of the long-necked dinosaur Camarasaurus is visible in a hard sandstone ledge. (Why is no-one excavating this dinosaur? Because we already have many nice specimens of Camarasaurus, and the sandstone around this one is like concrete. It would be a mountain of work for very little payoff.)

We spent about two hours measuring and photographing the skeleton, and as we did so, the clouds started to break up a bit. By the time we got back to Fruita, a little after 11:00 AM, the sky was clear except for a few scattered wisps of cloud. I set up my telescope in front of the Dinosaur Journey museum and started watching and photographing the transit.

Mercury transit 9 May 2016 - Mercury crossing the sun

I was using the same setup as in the last post: my Celestron C80ED refractor, a Celestron 8-24mm zoom eyepiece, and a GoSky full aperture solar film filter. For photography, I used a Nikon Coolpix 4500 for still photos and my iPhone 5c for video.

I caught about the last hour of the transit, and I got to share the view with about a dozen museum staff and passersby. A few light clouds drifted through the field of view, which looked pretty cool and didn’t obscure the view at all.

At 12:42 Mercury finished exiting the disk of the sun. The next Mercury transit will be in 2019 – I hope I’m as lucky then as I was this time.


We’ve been through this Pluto thing before

February 17, 2016

Pluto and other former planets

Mike Taylor sent me a link to this post on Quora about why Pluto should still be called a planet. Here’s the response I sent back after reading that piece, only lightly edited and with some links added:

I am unmoved. If we go back to the classical definition of planets as “wanderers” then there are 7: the sun, moon, Mercury, Venus, Mars, Jupiter, and Saturn. Clearly we have the ability to redefine the term from “naked-eye visible objects that move against the background stars as seen from Earth” to “big round things that orbit the sun”.

As for the idea that Pluto was a planet for 70-odd years before being demoted, so what? Ceres and Vesta were planets for half a century, and Juno and Vesta were planets for more than 40 years. Eventually people decided that it was unworkable to classify everything in the rocky belt between Mars and Jupiter as a planet – asteroids are a different class of objects, and referring to them as planets conflates two very different phenomena. Recently many people – an acting majority – have decided that it is equally unworkable to classify everything in the icy belt beyond Neptune as a planet, for the same reason. Kuiper Belt objects are a fundamentally different kind of thing from either the rocky planets or the gas giants. We’ve been through all of this before. We can have 8 planets, or hundreds.

Finally, I am completely opposed to this essentialist idea that terms have to keep their meaning forever and aren’t available for revision as we learn more. I think it’s a harmful doctrine, not least because it’s strongly at odds with the reality of how people actually use language – in science, and in all other areas of life.

That said, thanks for the link. I haven’t seen the pro-Pluto argument couched quite that way before. I disagree with almost all of it, but it’s still useful to know that people think that way.

To which Mike replied:

I’d agree with pretty much all of that, for what it’s worth. I thought it was interesting to see the strongest case made for Pluto’s planetary status by someone with a stake and some expertise, and then to see how far short of being persuasive that was.

What do you think?


Observing Reports: two perfect imperfect nights at the Salton Sea

November 23, 2015

Apex 127 ready for stars 2015-11-14

The Saturday before last, November 14, I was at the Salton Sea with Terry Nakazono.

Terry Nakazono with Meade Polaris 114 2015-11-14

Terry was rolling with a new scope – a Meade Polaris 114. It’s an f/8.8 reflector – the 1000mm focal length makes it a bit longer than the 900mm, f/7.9 Orion XT4.5 (which London has). UPDATE Nov. 29: Terry writes, “It’s a standard 900mm FL, not 1000mm. A lot of the retailer ads have it wrong and says its 1000mm. I myself was intrigued when I first read about it, but later found out from looking at the PDF manual and those who bought it is that it is an F/7.9 of 900mm focal length.” So it’s not longer than London’s XT4.5, it’s essentially the same OTA.

This Meade is a pretty amazing deal. A lot of small intro reflectors have a short dovetail bar bolted to the side of the tube (like my old scope Shorty Fats), but this one has real tube rings and an EQ-2 mount. The three MA (Modified Achromat) eyepieces it comes with are nothing to write home about, but the focal lengths of 26mm, 9mm, and 6.3mm are at least useful and non-overlapping when doubled with the included Barlow. Terry shared a few views with me and I can confirm that it serves up a sharp, contrasty image, as you’d expect for a scope of this focal ratio. It would be a good deal at the list price of $170, but Amazon has it for $135 as of this writing, and according to Terry it can be found for even less if you look around.

Matt aligning finder on Apex 127

I brought the Apex 127/SV50 combo – I’m sighting on the moon here, to align the finder with the scope – and the C80ED.

Matt digiscoping moon

Here I am digiscoping the moon with the C80ED. I used the Apex 127 for tracking down some planetary nebulae and double stars, and the C80ED for photography and just messing around. It’s a crazy fun little scope. Unfortunately, none of my moon shots worked out this time.

The forecast called for clear skies most of the night, but clouds between 10:00 PM and 2:00 AM. We got set up before the sun set at 4:45, and pushed through until 10:40. Then it got too hazy to observe, so Terry and I sat and jawed about scopes, atlases, and observing projects until the sky cleared a bit at midnight. We got in about half an hour more before the sky clouded over completely about 12:40. We talked a bit more then turned in.

Jupiter and moons 0530 PST 2015-11-15

I got up at 4:00 AM to catch the morning planets – Jupiter, Mars, and Venus. I cannot get the iPhone to take a fast enough picture to capture any detail on Jupiter – it always comes out as a blank circle of light (with some glare from the iPhone, not the scope). But the moons show up nicely. I really need to get a better camera control app.

Clouds at dawn 2015-11-15

I was clouded out again at 5:15, and Terry and I sat up until 5:45 watching the approaching dawn. Then it started sprinkling! Weather Underground, the Clear Sky Chart, and my other weather app all missed that. We packed up quickly and drove out at 6:30. A hearty breakfast at the Coco’s in Indio put a cap on the expedition. Although the skies were less than perfect, we had a good time catching up, and we did see some nice things.

Waxing gibbous moon 2015-11-22

Back Again

As luck would have it, I was back at the sea just eight nights later. London and I hadn’t been to the Salton Sea since last November, and he has all this week off from school, so we went last night. He took his XT4.5, and I took my C80ED. The waxing gibbous moon was only three days short of full, so the skyglow was pretty bad. But the seeing was excellent, easily 8 or 9 out of 10. I could split the four main stars of Orion’s Trapezium wide open at 25x, and fleetingly at 19x with the 32mm Plossl.

I could have held that split more easily with a better low-power eyepiece. I had not noticed it before last night, but my trusty Orion Sirius 32mm Plossl, my go-to widefield and finder eyepiece for many years, has some astigmatism. Not a lot – it was only noticeable immediately after switching from my 24mm ES 68. I tried both eyepieces with and without eyeglasses to confirm that the aberration was in the Plossl and not elsewhere in the optical train, my eyeballs included (I tried both). Another case of getting spoiled by premium eyepieces. It’s fine, though – since the 24mm ES 68 gives the same field of view, I only pull out the 32mm Plossl when I want to drop the magnification even lower, or when I’m doing outreach.

Sigma Orionis sketch 2015-11-22

I spent a lot of time cruising the central part of Orion at 120x with the 5mm Meade MWA, which is now my preferred high-power eyepiece. Just three weeks ago I saw and sketched the multiple star Sigma Orionis for the first time. It’s funny – I’d been observing Orion regularly for eight years before that and I’d never seen it, but now I stop there every night I have a scope out. Even London’s little 60mm Meade refractor split the six main components wide open. But last night I saw a faint, seventh member that I’d previously missed.

I turned in relatively early, around midnight, figuring that I’d get up after the moon set and do a quick morning Messier hunt. And the sky was truly phenomenal after moonset. I was waking up about once an hour and having a quick look around, and it was a spectacularly clear, dark night. But the flesh was weak, and I overslept, only dragging myself out of my sleeping bag at 5:00. By that time the first glimmerings of dawn were lighting the eastern horizon, so I skipped the Messiers and went to Jupiter.


That planet above the scope is Venus, not Jupiter.

The view was jaw-dropping. The seeing was rock solid and I was able to Barlow the 5mm MWA up to 240x without the image breaking down. At that magnification I could detect at least three delicate brown belts north of the North Equatorial Belt, and the Galilean moons were little spheres, not just points of light. I tried taking some pictures but didn’t get any better results than I had the last time out, so I put the camera away and just stared. I must have spent 45 minutes just watching Jupiter drift across the field of view, mostly at 240x.

Last night I was definitely in aesthetic observing mode. I spent a little over two and a half hours at the eyepiece, entirely on four objects – the moon, Orion nebula and Trapezium, Sigma Orionis, and Jupiter. I had half-formed plans to look at other things, but I kept getting seduced into long sessions of fully immersed stargazing. And I’d do it again in a heartbeat.


So, neither night had perfect observing conditions. It was hazy the first night, and the moon was out during the convenient observing hours last night. But I had a great time both nights, saw some cool things, learned a little more about my gear, and enjoyed the good company of Terry and London. Couldn’t really ask for more.


Observing Report: PVAA star party on Mount Baldy

April 22, 2015

PVAA Mt Baldy Star Party 2015-04-15 panorama

Last Saturday a bunch of us from the Pomona Valley Amateur Astronomers, plus a few folks from neighboring clubs, got together at Cow Canyon Saddle on Mount Baldy for the monthly PVAA star party. Here’s a panorama of the whole group while we were setting up before sunset. It’s worth clicking on to scan around the full-size image. I wasn’t holding a camera on a tilt, the parking lot really does slope down significantly from northeast (right) to southwest (left).

PVAA Mt Baldy Star Party 2015-04-15 west end group

I spent most of the early evening with these folks at the southwest end of things. From left to right here we have Cori Charles, our local outreach coordinator for the Planetary Society; my son, London, with his XT4.5; Gary Thompson, our club treasurer – his powder-blue 8-in Dob is mostly hidden behind London; Rob Record of the Riverside Astronomical Society with his C6 SCT; and Terry Nakazono with his StarBlast 4.5EQ. My Celestron C80ED is in the right foreground, and with Venus in the photo near the bottom of this post.

PVAA Mt Baldy Star Party 2015-04-15 Kassandra and Kevin Garcia

Here are Kassandra and Kevin Garcia with their 8-inch SCT – they treated all of us to a steady stream of wonderful views.

I didn’t get pictures of everyone and their scopes. People I missed included Bill Maxey and his Vixen VMC 200L, Brandon Finnegan and his XT8, Frank Nelson, some folks who came while I was out and brought a Celestron FirstScope, and possibly others. And I haven’t mentioned Ed Grobel and Patty Morrison yet…

PVAA Mt Baldy Star Party 2015-04-15 Patty Morrison

Ed and Patty are relatively new to amateur astronomy and to the club, but they are getting up to speed very fast. Here’s Patty looking at Jupiter through their Celestron NexStar 6 Evolution. Yes, that’s a bunny ear you can see on her hat. Ed was wearing a chicken hat, I think. I’m going to ask Patty to make me a dinosaur hat.

Anyway, in the early part of the evening I split my time between socializing, looking through other people’s scopes, and helping London with a few things, although he is pretty independent with the XT4.5. He found the Orion Nebula, the Pleiades, and the Beehive (M44) all by himself, and the open cluster M41 and the galaxy pair M81/M82 with just a little help from me. I also got nice views of Jupiter through several scopes, and Brandon Finnegan treated me to great views of the Sombrero Galaxy (M104) and the triple star Beta Monoceros in his XT8.

At around 10:00 I left to run London home, but I was back on the mountain by 11:00. After that, my own scope sat mostly neglected while I cadged looks off everyone else. I spent a lot of time, close to four hours, observing with Ed and Patty and their C6. I probably missed a few things, but a mostly-complete list of objects we looked at includes Comet Lovejoy – still surprisingly bright as it heads north out of the solar system – Jupiter, Saturn, M13, M5, M57, M81/M82, NGC 6543, the Leo Triplet, Epsilon Lyrae, Albireo, Polaris, M51 and NGC 5195, M4, M27, Brocchi’s Coathanger (in the finderscope of the XT4.5), Saturn again, Jupiter again, NGC 4565, and Saturn yet again to conclude.

PVAA Mt Baldy Star Party 2015-04-15 C80ED and Venus

For me, the best views of the night were of globular clusters and Saturn. There was a stretch around 11:30 when most of us still on the field went a little glob-mad. I looked at M13 through both of the C6 SCTs and through Gary’s 8-inch Dob. I was extremely impressed by the 6-inch SCTs. They gave up surprisingly little to the Dob in terms of image brightness and their long focal lengths and comparatively high magnifications meant that everything we looked at had a nice image scale. All of the globs we looked at in Ed’s and Patty’s scope had nicely resolved outer halos, and NGC 6543, the Cat’s Eye Nebula, was distinctly bluish-green in the eyepiece.

Then there was Saturn. Seeing was very good Saturday night and Saturn was just stunning. I have never been able to hold the Cassini Division in direct vision for so long at a time. Occasionally a random gust or roil would smear it out but it was easily visible at least 80% of the time. The disk of the planet showed salmon-colored bands, and we could make out the shadows of the rings on the planet, and of the planet on the rings, so dark and crisp they looked inked in. That’s why we kept going back for more.

After Ed and Patty packed up about 3:00 AM, I wussed out and crawled in the Mazda for a couple of hours of sleep. I had a couple of quick peeks with the XT4.5 after I got up, but by then the sky was starting to get bright. Terry had pushed right through with only a half hour catnap earlier in the evening, adding 7 or 8 new objects to his tally, which now includes over 1000 unique deep-sky objects. We packed up and went down the hill for breakfast. All in all, a great time.

Before the star party, someone wrote to Gary to ask if non-members are welcome at PVAA star parties. The answer is yes, always! If you are within striking distance, come on out and see some things with us. Our star party calendar and directions are available on the PVAA website, I hope to see you out there.


Chasing Comet Lovejoy

February 4, 2015

I’ve been out a few times in the last few weeks, mostly to see comet 2014 Q2/Lovejoy. It’s still nice and bright and it’s an easy catch in binoculars. You can get up-to-date finder charts from Heavens Above.

Our notes from January 17 - Steve's sketch of Jupiter and my sketches of the Trapezium and comet Lovejoy.

Our notes from January 17 – Steve’s sketch of Jupiter and my sketches of the Trapezium and comet Lovejoy.

About three weeks ago now, on January 17, I was up at the Webb Schools observatory with Steve Sittig, who you’ll recall from the virtual star party, last summer’s birthday observing run, and – farther back, in 2010 – comet 103P/Hartley. We were using the equatorially mounted C14 in the Webb Schools’ Hefner Observatory. We started on Orion just to get warmed up, and we could easily see the E and F stars in the Trapezium. After that we went after the comet. It was kind of a comedy of errors. We had problems getting the telescope pointed where we needed it, and neither of us had seen the comet yet so we were a little unsure of where to look. Finally we started scanning around with binoculars and then the comet was an easy catch, and we were able to get the scope on target. I made a couple of sketches a few minutes apart that show the comet moving through the field, but the western sky was getting hazy and pretty soon the comet was lost to us.

Jupiter from Webb - Jan 17 2015 - with labels

Jupiter and the four Galilean moons on January 17, 2015. Click through to see the moons. Photo by Steve Sittig.

After that we turned east to have a look at Jupiter. Steve made a sketch and got some photos with his DSLR mounted to the C14. As is usually the case, the photos do not nearly capture all of the detail that we could see at the eyepiece. We could see many cloud bands at high latitudes, and north and south equatorial belts were highly detailed with ruffled edges and festoons. Io was distinctly yellow at the eyepiece, much more so than the other moons, which ranged from white to a very faint blue. Thanks to Steve for the photos and for the great, if brief, night of stargazing.

Comet Lovejoy 2015-01-24 invert

The next Saturday, January 24, London and I set up telescopes in the driveway and took in some of the best and brightest objects (most of which London found himself!). I sketched the comet a couple of times, to show it moving against the background starfield.

I have another long-delayed observing report, from a trip to Anza-Borrego Desert State Park late last fall, but that will have to wait for another time.


Earth-moon distance and the diameters of the planets

June 15, 2014

A few days ago Mike sent me this:

Earth-moon distance and planetary diameters

I was surprised to see so many people calling BS on this–it’s simple enough to double-check. So I did. Here are the results.

Mean radii in km, from Wikipedia:

  • Mercury – 2400
  • Venus – 6100
  • Mars – 3400
  • Jupiter – 69,900
  • Saturn – 58,200
  • Uranus – 25,400
  • Neptune – 24,600
  • Total – 190,000

Doubled, to convert to diameters – 380,000 km

Average Earth-moon distance, also from Wikipedia: 384,000 km.

Yep, this checks out. With the proviso that the Earth-moon distance actually varies from 363,000 to 405,000 km, so sometimes you’d have to leave out Mars and Venus, and other times you’d have to clone them to fill the extra space.

If you want a remarkable coincidence, the moon formed maybe only 10,000 miles from Earth and has been gradually receding ever since. So we are living in the tiny slice of Earth history when the moon is at just the right distance to appear the same relative size as the sun, and thus produce total eclipses as we know them. Annular eclipses have only been around for a few tens of millions of years, and in another few tens of millions of years, they’re all we’ll ever get, because the moon will be too distant to completely block the sun.

Anyway, after I sent Mike this reply, he said, “That is a whole lot of awesome, which clearly ought to be a 10MA post”. And now it is.

UPDATE October 13, 2014: A much more detailed explanation of the end of total solar eclipses in the distant future can be found on this page, under the “Final Totality” heading.


Hell yes–wheels down on Mars again!

August 6, 2012

We all stayed up last night to watch Curiosity land on Mars. It was amazing, to be watching the live feed from Mission Control at JPL, hearing the live telemetry being relayed, and then just moments after touchdown get to see the first photo sent back by the rover (it’s grainy and blurry because the transparent lens cap is still on the camera to protect it from the dust kicked up by the landing).

As John Holdren, President Obama’s assistant for science and technology, said, “there’s a one ton automobile-sized piece of American ingenuity and it’s sitting on the surface of Mars right now.”

I was particularly engaged because I had gotten to see parts of the actual spacecraft, including the aeroshell and rocket skycrane, during a tour of JPL two and a half years ago. Strange and amazing to know that the same machinery I saw in the big white room at JPL is now on Mars.

During the landing, data were relayed  back by the Mars Odyssey spacecraft, which has been in orbit around Mars for 10 years, 9 months, and 13 days. This decade-old craft was never designed to function as a data relay, but, you know, engineers are smart. Curiosity joins the rover Opportunity, which is still going strong 3116 days into its 92.5-day mission.

Turns out, we weren’t the only ones watching the landing. The Mars Reconnaissance Orbiter got a photo of Curiosity on the way down, using its HiRISE camera.

This is the second time MRO has caught a Mars lander on the way down; it got a photo of Phoenix descending under its parachute back in 2008.

Happily, today’s xkcd explains why I’m blogging about space on a Monday morning:

Or, as my buddy Jarrod put it on Facebook, “We just landed a one-ton NUCLEAR ROBOT on another planet with a SUPERSONIC PARACHUTE and a FRICKIN’ ROCKET SKYCRANE.”

Good times.