Duncan Steel

Duncan Steel is based in Nelson but works for the Xerra Earth Observation Institute with its HQ in Alexandra. He has worked in space research for almost forty years, with times spent with NASA, ESA, various universities and observatories, and also running his own company. Duncan is the author of four books, over a hundred research papers, and more than a thousand articles for newspapers and magazines. He has also appeared in hundreds of radio and TV programmes. Minor planet/asteroid (4713) Steel is named for him, as is a lunar-roving robot in one of Arthur C. Clarke's SciFi novels.

Apollo 11 and the Real Dish - Out of Space

Jul 16, 2019

The TV pictures of Neil Armstrong clambering down the ladder of the Apollo 11 Lunar Excursion Module and taking the first steps by a human on the Moon’s surface are rightly iconic, though rather fuzzy. Most people seem to think that those images were received by the radio telescope at Parkes in New South Wales, largely because that was what was depicted in a popular Australian movie entitled ‘The Dish’. The truth, however, is that those pictures were grainy in part because they were actually received using a rather smaller antenna, located at a tracking station close to Canberra that few people have heard about: Honeysuckle Creek.  Whenever a movie appears on TV and it starts with a statement that it is “Based on a True Story”, I switch it off (or at least leave the room, so as to … Read More

The Equation of Time - Out of Space

Jul 14, 2019

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 fortnight after the solstice, whereas the earliest sunset happened around a week before the solstice and so began progressing later before the solstice was reached. The reason for these surprising facts are all tied up with the equation of time, a graph of which is shown on many good sundials. But what causes these apparent discrepancies, to which we are largely oblivious?  It had been my intention to write this blog post on July 5th, for reasons that will become … Read More

Orbits of the satellites launched by Rocket Lab three days ago - Out of Space

Jul 02, 2019

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 by Rocket Lab through to that date. Following the launch last Saturday I added a note to that post, as follows: Update (June 30th): Congratulations to Rocket Lab on another successful launch yesterday. I will post here graphics and a movie of the orbits of the seven deployed satellites as soon as possible (perhaps a few days). The present post fulfills that promise (or maybe it was a threat…). The June 29th launch was given the name Make It Rain. Information … Read More

Asteroid Day… and what may follow - Out of Space

Jun 30, 2019

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 year: the anniversary of the Tunguska event in 1908. All around the globe there are meetings, talks, TV and radio shows, and newspaper articles, discussing the hazard that asteroids and comets pose to our civilisations. All around the globe, perhaps, but with little happening in New Zealand. Here on the Sciblogs website I have published two items of late concerning what we are doing about this surprising risk: Defending the planet from asteroids and Imagine an asteroid impact due … Read More

Tracking satellites launched from NZ - Out of Space

Jun 27, 2019

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, and of course one might find information about those in other ways. There are also many applications available to peruse what might be passing overhead at any time, plus sophisticated software tools that are free and make use of the very best algorithms for following how the various orbits alter over weeks and months.  In a press release issued yesterday the NZ Space Agency has announced that it has partnered with US company LeoLabs on a “project which … Read More

The day the Sun stood still - Out of Space

Jun 25, 2019

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 (and the reason for the festivities depicted by Shakespeare in the comedy whose title includes that word). There is also a serious side to this: few people (including many climatologists) seem to realise that the durations of the seasons are varying, and this might be a significant factor to encompass in climate change studies; quite apart from that, analysis of historical climate records should take into account the fact that the seasonal cycle was, until about 70/80 years ago, apparently … Read More

Murchison and geology - Out of Space

Jun 19, 2019

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 of some sort of anniversary. In recent weeks I have noted the centenary of the total solar eclipse of 1919, which demonstrated the veracity of Einstein’s General Theory of Relativity; the 250th anniversary of the observation of the transit of Venus by James Cook and his accompanying scientists from Tahiti; and the annual recurrence of Bloomsday. This week I have, however, missed the 90th anniversary of the Murchison earthquake of 17th June 1929, which killed 17 … Read More

Astronomy on Bloomsday - Out of Space

Jun 16, 2019

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 known as a Faraday cage,the function of which was the exclusion of extraneous radio signals. Quite apart from his scientific discoveries, there is something else that has been passed down to me from Faraday. He was a renowned public speaker, and one of his cardinal rules for giving a lecture was this: Never begin a talk with an apology. How true that imperative is. Many, many times I have sat in an audience and heard the speaker start by … Read More

Connecting comets and rubber - Out of Space

Jun 11, 2019

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 brother of the latter (George Skellerup) moved to New Zealand in 1902, and established the iconic NZ rubber company.  It being my birthday, I thought that the occasion should be marked with a blog post. But about what? My quandary was solved when my partner Jan presented me with a splendid pair of gumboots. And here they are:   Now, perhaps (like the BBC) the Science Media Centre might eschew any advertising, but it happens that … Read More

The problem of knowing when a lunar year begins and ends - Out of Space

Jun 05, 2019

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 matter that is briefly explained here.  Most of us are habituated to the use of a calendar based on how long it takes the Earth to orbit the Sun (for present purposes, a ‘solar year’), and it is such a system that is used as the global standard in all but a few places (such as North Korea) for ease of international communications. Very often people refer to this as the ‘Gregorian calendar’, but it is not. It seems self-evident … Read More