Category: Astronomy

The International Space Station (ISS) pass overhead twice while we were in the pub garden last night. It often does, obviously, and none of was simply seeing double. There are numerous websites that let you know when you can next see the ISS pass over your neighbourhood, VirtualAstro on Twitter puts out alerts, and thare are also smart phone apps that will push a timely notification.

Here are a few facts about the ISS:

• First component launched into orbit 1998
• Final pressurised module fitted in 2011
• Total cost estimated in 2010 as $150 billion
• Anticipated operation until 2028, extended from 2024
• Some components might be re-used to build a new space station
• ISS is a joint project between NASA, Roscosmos, JAXA, ESA, and CSA
• 109 x 73 metres, with solar panels extended
• 408 tonnes
• Orbits at an altitude of between 330 and 435 kilometres
• Makes about 15 orbits of the Earth each day
• Takes 90 minutes to make one orbit
• Travels at a speed of approximately 28000 km/h
• Visible with the naked if you are in the right place at the right time
• Appears as a slow-moving, bright white dot (reflected sunlight)
• Takes about 10 minutes to pass from one horizon to another, but only visible when not in the Earth’s shadow
• Continuously occupied since 2nd November 2000
• 145 people from the USA and 46 from Russia have been aboard, plus people from 16 other nations as of January 2018
• Since the end of NASA’s Space Shuttle program, Russian Soyuz rockets used to transport supplies and crew
• In low orbit, the crew is protected from the Solar wind by the Earth’s magnetic field
• They have a safe space for increased protection if a solar flare is heading their way
• Main roles: laboratory, observatory, and factory
• Additional purposes: staging base for future Moon, Mars, and asteroid missions
• Other uses: commercial, diplomatic, and educational
• The toilets are fitted with spring-loaded restraining bars to ensure a good seal
• Solid waste is bagged and brought back down to Earth
• Urine is recycled into drinking water on board

 

TL:DR – My sorry attempts at photographing Saturn and Jupiter in 2018.

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I love the late light of midsummer, the long, drawn out sunsets, the dying embers as our star ducks below the horizon, the afterglow, the gradual emergence of the stars and planets. Jupiter and Venus in opposite skies last night. Venus lamenting the Sun’s demise and hugging the sun North Western sky as we approach the solstice. Jupiter higher and dominant in the South. The asterisms we know as the Northern Cross and The Plough way above.

I was pondering life, the universe, and everything when it occurred to me that there was no moon last night. So, I grabbed my Canon dSLR and Sigma 150-600mm zoom lens in the hopes of snatching a glimpse of Jupiter’s moons, the four Galilean moons to be specific.  I’ve tried before with this camera setup and got something bearable, but although I could see Jupiter was very much not simply a stellar pinprick in the frame, the moons did not show up in this frame.

Perhaps, they’re eclipsed right now, hiding behind their giant gaseous parent, or maybe it was more about camera settings. It was too late in the evening after a day with a heavy workload to hunker down with tripod and remote shutter to get a longer exposure. Anyway, here’s a crop of the best of a handful of Jovial shots.

In the above shot, you can just about see the striations that band Jupiter, although you obviously cannot discern its Red Spot (which apparently has shrunk in size since I first read a stars and planets book as a child in the early 1970s). Settings were: Handheld with two-stop image stabilisation, full-frame camera, 600mm zoom, f/5.6, t 1/1500s, ISO 12800.

The shot was good enough to inspire me to turn my attention to Saturn, but I needed to find it in the night sky first. A quick look at a sky map revealed it was above the horizon in the Southern sky some way East of Jupiter and much lower. Spotted from “down the street”, a fairly orangey, diffuse-looking star. I didn’t feel like setting up the tripod (moreover the street lamps were going to spoil the view with their brightness, anyway. I didn’t have high hopes. I used the same camera settings, and was really surprised with what came out of the camera. Obviously, the photo is cropped, but you can clearly see Saturn’s rings in this shot.

I posted this photo to some acclaim on Facebook a few moments after snapping it and one commenter suggested they might buy a similar 600mm lens. I should point out that there’s a Tamron equivalent of the Sigma I use. Reviews say it is marginally better. That said, if you calibrate the Sigma to your specific camera you can adjust back/foreward focusing and improve clarity somewhat, I discussed this on the blog last year; you should calibrate all your lenses to your camera(s). If you don’t want to go to the expense of a full-blown astro kit (telescope and dSLR adapter), I reckon it would be worth buying the associated 1.4x multiplier for the Sigma or Tamron.

Conventional astronomical wisdom (as cribbed from Wikipedia) suggests that the Moon formed from the debris left behind when an object the size of Mars collided with the Earth about 4.5 billion years ago in the Hadean aeon, just a few dozen million years after the solar system itself first coalesced. This is the known as giant-impact hypothesis, the Big Splash, or the Theia Impact.

A new theory suggests that this may not be quite right. Instead, it seems there is evidence to suggest that the Moon actually formed within a spinning cloud of vaporized Earth following a collision, this spinning object is known as a synestia which would have been in orbit around the early Earth.

Sarah Stewart of the University of California Davis, USA points out that, “The Moon is chemically almost the same as the Earth, but with some differences.” It is those differences that have led to various hypotheses about the Moon’s formation. Now, Stewart and her colleagues have developed a new picture that meshes more closely with the differences in composition of the Moon and the Earth.

More here.