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.

Tiny asteroid whizzing past Earth today - Out of Space

Jul 28, 2020

Four weeks ago I wrote about the last time a sizable asteroid hit our planet – the ‘Tunguska Event’ of 1908, when an object about 50 metres across exploded above the Siberian taiga – but smaller cosmic rocks shoot close by Earth fairly frequently. In the past 42 hours (as I write) a tiny asteroid less than five metres in size has been discovered by astronomers in Arizona, tracked from Mt John Observatory in New Zealand, and then additionally followed by observers in Croatia and France. As a result we know it will miss us, but will today fly by at a distance that is less than the altitude of geostationary satellites. This asteroid is called 2020 OY4. The ‘2020’, obviously-enough, is the year of discovery. The ‘O’ denotes the half-month of discovery (the second half of July): we … Read More

The day the sky fell in - Out of Space

Jun 30, 2020

It’s June 30th, marked as Asteroid Day by many people of an astronomical bent around the globe. On this date in 1908, early in the morning in a remote part of central Siberia, the sky fell in. Well, not literally. What happened is a substantially-sized bit of cosmic detritus – a lump of rock and perhaps ice – arrived in the upper atmosphere at a speed of around 30 kilometres per second (108,000 kph). It was about 50 metres in size, based on a stone-like density and an energy release that has been estimated as being between 3 and 20 megatonnes of TNT equivalent. Compare that with the Hiroshima nuclear bomb, at 15 kilotonnes about a thousand times less energetic. This was some big bang. This occurrence is generally known as the Tunguska Event (for the Podkamennaya Tunguska … Read More

The fate of the albatross - Out of Space

Jun 19, 2020

Yesterday I wrote that I can find some reason to celebrate almost any date, and today (19th June) is no exception: it’s World Albatross Day. Unfortunately the day began with a news story concerning a commercial fishing boat killing four endangered Antipodean albatrosses off NZ’s East Cape. Even more unfortunately, such events are not unusual, with several others media stories this year concerning the loss of albatrosses and other seabirds as a consequence of commercial fishing (for example, see here, and here, and here). Clearly there are reasons for concern. In my post yesterday about Wellington and Nelson I wrote that there was not much about astronomy or space (my usual subjects) involved. In the present blog post there is, in fact, a bit of an astronomy connection, and I will come to … Read More

Connecting Wellington and Nelson - Out of Space

Jun 18, 2020

My blog post here has essentially nothing to do with space and astronomy, my usual subjects, but it concerns a little matter of history I thought I’d like to write about. Once upon a time I wrote a long book about calendars, and as a consequence accumulated knowledge about many of the special dates in the year which could be used as an excuse for having a beer. Two days ago it was Bloomsday, a good reason for a Guinness (and also for giving flowers to someone: my doctor’s surgery staff kindly obliged me by accepting a bunch of yellow roses). Although the hours are running out, today is June 18th, and so the 205th anniversary of the Battle of Waterloo. I imagine that many today know about it mainly from the song by ABBA, but the battle … Read More

Where is New Zealand’s highest point? - Out of Space

May 01, 2020

Did you know that the top of Mount Cook is by no means New Zealand’s furthest point from the centre of the Earth? And that Samoa’s tallest mountain is seven kilometres further from our planet’s core than anywhere in NZ? The highest point anywhere, in terms of separation from Earth’s centre? — It’s not Mount Everest.  It’s the sort of question that gets asked as a tie-breaker in a pub quiz: I am stood on the point on Earth’s surface that is furthest from its centre. My feet are two-feet apart (of course) along a north-south line. Which country is each foot in?  Cue for head-scratching and debate. Most people think that the point in question is the top of Mount Everest, and some know the border between Nepal and Tibet (as claimed by China) goes through that peak. In consequence … Read More

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