Out of Space

The Equation of Time

Duncan Steel • Jul 14, 2019

• Aphelion,
• astronomy,
• day length,
• Equation of Time,
• Meridian,
• Perihelion,
• solstice,
• Sun,
• Sunrise,
• sunset

The solstice on June 22nd marked the shortest duration of sunlight (or day length) during this year. One might have expected that from that date sunrise would have started getting earlier; and prior to that date sunset to have been consistently getting earlier (as the daylight duration was shortening). In fact the latest sunrise did not occur until almost a … Read More

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Orbits of the satellites launched by Rocket Lab three days ago

Duncan Steel • Jul 02, 2019

• apogee kick motor,
• rocket lab,
• rockets,
• satellites,
• space,
• space launch

On Saturday June 29th Rocket Lab launched another cluster of seven satellites into low-Earth orbit from the Mahia Peninsula in New Zealand’s North Island. In this blog post I illustrate the orbital paths of the ten resultant tracked items now in orbit.  In a blog post last week (June 27th) I showed the orbits of the various satellites launched … Read More

Asteroid Day… and what may follow

Duncan Steel • Jun 30, 2019

• asteroids,
• Chelyabinsk meteor,
• Coherent Catastrophism,
• comets,
• cosmic impacts,
• meteor showers,
• meteorites,
• meteoroid streams,
• meteoroids,
• meteors,
• planetary defence,
• Stochastic Catastrophism,
• Tunguska event

The Tunguska explosion in 1908 was due to the arrival of a small (perhaps 50 metre) cosmic object, quite likely a fragment of a known comet. Astronomers are now wondering whether siblings of that projectile might pass close by the Earth over the next week or so.  I write tonight on Asteroid Day, which occurs on June 30th each … Read More

Tracking satellites launched from NZ

Duncan Steel • Jun 27, 2019

• CubeSats,
• Low Earth orbit,
• Orbits,
• rocket lab,
• satellites,
• Space debris,
• space tracking

With so many thousand satellites now in orbit, and tens of thousands of other tracked items, one might think that it is difficult keeping tabs on them, simply as an interested person. In fact it is quite straightforward, with long lists of orbital elements freely available for all except the few satellites deemed by the US Government to require secrecy, … Read More

The day the Sun stood still

Duncan Steel • Jun 25, 2019

• anomalistic year,
• climate analysis,
• Equinoxes,
• Latin,
• matariki,
• mean tropical year,
• Pleiades,
• seasonal cycle,
• seasons,
• Solar eclipse,
• Solstices,
• Subaru

We have just passed the solstice, the shortest day of the year in the southern hemisphere. From now on, the hours of daylight will get longer through until the December solstice. Here I discuss why the June solstice occurs a few days before the Feast Day of St John the Baptist, the traditional time of ‘midsummer’ in the northern hemisphere … Read More

Murchison and geology

Duncan Steel • Jun 19, 2019

• carbonaceous chondrites,
• earthquakes,
• geology,
• Inangahua earthquake,
• lunar craters,
• meteorites,
• Murchison,
• Murchison earthquake,
• permian period,
• radio astronomy,
• silurian period,
• Sir Charles Lyell,
• Sir Roderick Murchison

There are many places, both in New Zealand and elsewhere around the globe, that are named for the nineteenth-century Scottish geologist Sir Roderick Impey Murchison. It seems astonishing how many of these are connected in some way with events of geological significance, or are otherwise of scientific importance.  One of my predilections is writing blog posts prompted by the occurrence … Read More

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Astronomy on Bloomsday

Duncan Steel • Jun 16, 2019

• astronomy,
• Bloomsday,
• comets,
• Daedalus,
• Greek mythology,
• Homer's Odyssey,
• Icarus,
• Ithaca,
• James Joyce,
• Leopold Bloom,
• Literature,
• Molly Bloom,
• moon,
• Nora Barnacle,
• Odysseus,
• Stephen Dedalus,
• supernovae,
• Tycho Brahe,
• Ulysses

The name of Michael Faraday is well-known in science, for his pioneering work in both chemistry and physics (in particular electricity and magnetism; hence the name of the SI unit of capacitance, the farad). As a postgraduate student at the University of Canterbury I spent many hours working on experimental radio receivers sat inside a large metallic box … Read More

Connecting comets and rubber

Duncan Steel • Jun 11, 2019

• astronomy,
• Comet Grigg-Skjellerup,
• comets,
• Frank Skjellerup,
• George Skellerup,
• gumboots,
• John Grigg,
• New Zealand,
• rubber,
• Skellerup family,
• Skellerup Holdings Limited Group,
• Skellerup Industries Limited

Comet Grigg-Skjellerup was one of the first such celestial bodies to be visited by a spacecraft, the Giotto probe which was sent on to encounter it in mid-1992 after having first visited the famous Comet Halley in 1986. Comet Grigg-Skjellerup was discovered about a century ago, independently by a New Zealander (John Grigg) and an Australian (Frank Skjellerup). The younger … Read More

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The problem of knowing when a lunar year begins and ends

Duncan Steel • Jun 05, 2019

• Calendars,
• conjunction,
• history of astronomy,
• Islamic calendar,
• lunar calendars,
• lunar months,
• lunations,
• luni-solar calendars,
• moon,
• new moon,
• solar calendars,
• synodic months

The Islamic fast of Ramadan has come to an end, marking the beginning of the tenth month of the religion’s twelve-lunation year and therefore Eid al-Fidr, the ‘Festival of Breaking the Fast’. How the decision is made when each of those months begins and ends depends upon the actual sighting of the crescent new moon in the sky, a highly-complicated … Read More

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The 250th anniversary of Cook’s observation of the transit of Venus

Duncan Steel • Jun 02, 2019

• astronomy,
• History of New Zealand,
• HM Bark Endeavour,
• James Cook,
• Mercury,
• Mercury Bay,
• New Zealand,
• Pacific,
• South Pacific,
• Sun,
• Tahiti,
• Transit of Mercury,
• transit of venus,
• Venus

On June 3rd occurs the 250th anniversary of the transit of Venus across the face of the Sun, the observation of which was the prime purpose behind the expedition of HM Bark Endeavour to the South Pacific, under the command of Lieutenant James Cook. Following the measurements of the transit made by Cook and the mission’s scientists in Tahiti, the … Read More

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