Duncan Steel

Duncan Steel is a space scientist based in Nelson. He has worked in scientific research for over 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.

When is the day inserted into a leap year? - Out of Space

Feb 24, 2020

Surprisingly enough, one could argue (as I often do) that the day inserted into a leap year is not that we label 29th February, but actually the 24th of February. Here I explain why, briefly.  Almost everyone assumes that the day added into February in a leap year is the 29th, but that assumption is based on a lack of knowledge of how our calendar has evolved over the centuries, subject to manifold influences of history, contingent events, and most-especially various religious considerations. Historically-speaking, the day added is that we call February 24th [sic], as I will explain. However, to jump to the punch line, the British decision to conform to the dating system of the Gregorian/Catholic calendar from the mid-18th century actually states rather simply that the day to be added is the 29th [sic, again]. This is what … Read More

New launch of 60 SpaceX satellites crossing NZ - Out of Space

Feb 22, 2020

Last Monday SpaceX launched another clutch of Starlink satellites into low-Earth orbit, bringing up to 300 the number of these units intended to bring 5G internet to the whole globe. In this post I present a movie showing how all 300 such satellites will be zipping around our planet over the next eight days (until the end of the month), also showing still shots for the times when this latest batch should be visible from New Zealand in the evenings of the next week or so.  In previous posts (linked here and here) I have written about the chains of satellites observable in the evening sky an hour or so after sunset some days, or in the morning sky an hour or so prior to sunrise. That is, the satellites are in direct sunlight at their high altitude … Read More

Update on how to see the Space-X satellite chains from NZ - Out of Space

Feb 08, 2020

In a previous post I described briefly when and how the Starlink satellite chains – recent launches by Space-X in a scheme to bring 5G internet connectivity to the whole globe – could be seen from New Zealand with the naked eye. Here I provide an update and predictions for the next several days.  My preceding post included a link to a movie showing how the Starlink satellite chains will cross the sky near New Zealand in the evenings of February 5th-9th. An updated movie available here shows the passages on February 7th-11th by the various Starlink satellites in both the pre-dawn and the post-dusk timeframes for NZ, these being the times of day in which NZ residents will have a dark sky and yet the satellites will still be bathed in sunlight at their orbital … Read More

Seeing the Space-X satellite chains from NZ - Out of Space

Feb 04, 2020

Space-X has started launching its Starlink satellites into low-Earth orbit with a plan to use some tens of thousands of these to deliver 5G wifi to the whole globe. Chains of these satellites can be seen in the evening or before-dawn skies, through the sunlight they scatter. Here I provide a movie showing opportunities for spotting such satellites over the next few days (through to February 9th). A Starlink satellite chain should be visible from Wellington during the Queen + Adam Lambert concert on Wednesday evening.  The constellation of Starlink satellites has recently been boosted with another Space-X launch. There are now 242 such satellites in orbit, although so far as I have been able to determine only 237 of those are operational. In a movie available here I show how large numbers of those will pass over … Read More

Southern Cross and Pointers Painted Large Across Christchurch - Out of Space

Dec 25, 2019

Using knowledge of when the Sentinel-1A radar satellite was due to pass over New Zealand, a team at Christ’s College laid out specially-constructed radar retroreflectors across Hagley Park in Christchurch, in that way painting the Southern Cross and the Pointers in a huge array clearly visible in the derived radar image of the city.  A special – but brief – post for Christmas Day (with more details to follow in a later post). The image in the header above shows the Southern Cross (Crux Australis) and the Pointers (Alpha and Beta Centauri) painted large across Hagley Park in Christchurch, by Dr Andrew Taylor and a team of students from Christ’s College. Here is a wider view of the centre of Christchurch: Now, this is actually a radar image collected by the European Sentinel-1A satellite as it passed over New … Read More

Kiwi exoworlds are named - Out of Space

Dec 20, 2019

The International Astronomical Union (IAU) this year invited nations to propose names for distant stars selected on the basis of having planets (exoplanets) discovered to be orbiting them. The New Zealand entries, now adopted officially by the IAU, are Karaka for the star, and Kererū for its associated exoplanet.  In a previous blog post I described how New Zealanders had been invited to propose names for a distant star, and the planet (exoplanet) that had been discovered to be in orbit around it. And now the results are in… The announcement from Dr Nicholas Rattenbury at the University of Auckland reads as follows: Alternatively, one can look at the official International Astronomical Union (IAU) website to find the following: One could say that this is a year late, in that the kererū was … Read More

Among my favourite asteroids: (2309) Mr. Spock - Out of Space

Nov 27, 2019

Minor planet/asteroid (2309) Mr. Spock is named not for the character in Star Trek, but for a cat that was itself imperturbable, logical, intelligent and had pointed ears.  In a preceding blog post I introduced one of my favourite asteroids, (2472) Bradman, and also mentioned (6581) Sobers amongst a few others. I did have something to do with the naming of (2472) Bradman; but for (2309) Mr. Spock I can admit to no involvement whatsoever. Here is the citation for Mr. Spock and, surprise, surprise, it is not titled directly for the character of that name in the TV and movie series Star Trek: Named for the ginger short-haired tabby cat (1967- ) who selected the discoverer and his soon-to-be wife at a cat show in California and accompanied them to Connecticut, South Africa and … Read More

Among my favourite asteroids: (2472) Bradman - Out of Space

Nov 25, 2019

There are many thousands of asteroids with formal names, some humdrum but other more noteworthy (depending on your predilections). One of my favourites, the name of which I was involved in suggesting, is (2472) Bradman, named for the Australian cricketing great. After discussing (2472) Bradman, I also make some comments about (6581) Sobers.  As a minor planet (synonym: asteroid) spotter, I have had the privilege of proposing names for a dozen such celestial objects for which I was the formal discoverer. These are most-conveniently found on my Wikipedia page, being named for my two sons (Harry and Elliot), their mother, two of my undergraduate-student-days lecturers who were particularly pivotal in affecting my career and providing inspiration, the town near Bath where I was born, my four siblings including elder sister Karen and youngest sister … Read More

JFK’s assassination: a bit of physics - Out of Space

Nov 22, 2019

There are perennial arguments about the circumstances of the assassination of President Kennedy in 1963, and in particular whether more than one shooter is required by the evidence (such as the Zapruder film). Those who know little about physics frequently claim that the sharp backwards motion of JFK’s head as the fatal shot hit him is proof that there must have been a gunman in front of the car carrying Kennedy. This is simply untrue. As I show here, the movement of the head is consistent with a bullet arriving from behind, from Oswald on the sixth floor of the Texas Book Depository in Dealey Plaza, Dallas. There is no need, in terms of the physics, for a second gunman.   It’s that time of year again. On 22nd November 1963 (it was already the 23rd in New Zealand) President … Read More

Earth’s artificial rings - Out of Space

Nov 20, 2019

Satellites pass over NZ all the time (literally). Here I focus on the 187 Planet Labs ‘Dove’ Earth-imaging satellites, and I show that one can determine in advance where they will be, enabling scientists on the ground to correlate their environmental and other data collection with opportunities to get imaging from space. That is, we can get ‘space-truth’ (rather than ground-truth) for the various types of scientific  investigation underway in the wonderful natural laboratory known as Aotearoa/New Zealand.  When you work in a certain area of science and technology, generally you soon become rather blasé with regard to the reality of what your discipline entails. Familiarity breeds contempt, so the saying goes. This was brought home to me over the past month or so, when I was giving two talks in Auckland to two quite different groups of people. All … Read More