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.

Lunar eclipse on Wednesday - Out of Space

May 23, 2021

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Lunar eclipse visible from NZ on Wednesday There will be a total lunar eclipse to be seen from throughout Aotearoa New Zealand on the evening of Wednesday May 26th, easily visible to all just as long as clouds do not intervene. An eclipse of the Moon occurs when it passes close to opposite to the Sun in the sky, and so enters Earth’s shadow. While total solar eclipses – when the Moon comes between Earth and Sun – are rare events for any particular location on our planet, a total lunar eclipse can be witnessed from any point situated on the half of the globe in night-time. For this Wednesday’s event, one might say that NZ is ideally located (see the map at the head of this post), with the eclipse commencing around 9pm, … Read More

Great conjunctions and the star/comet of Bethlehem - Out of Space

Dec 20, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] There have been many articles in the mass media about the ‘Great Conjunction’ between Jupiter and Saturn that will occur on December 21st. Some of them have been good, and informative. Many have been fairly poor. Others have been… well, weird. Some writers have imagined that there is something vitally significant about the conjunction (the close approach to each other in the sky) of the two giant planets occurring on the same day as the solstice. That’s just by chance: there is no astronomical link between the two phenomena. From our perspective in the southern hemisphere the fact that the conjunction occurs at much the same time as the (austral) summer solstice is a bad thing, in that it reduces our opportunity to witness the coming-together of the planets. Here in the antipodes the conjunction … Read More

Big Eye Wide, But Shut - Out of Space

Nov 23, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] A few days ago the US National Science Foundation (NSF) announced the decommissioning of the Arecibo Observatory in Puerto Rico. This story has been the subject of items in the mass media around the globe, and also in New Zealand. Cables supporting the massive horns and radio receivers above the dish have snapped, the actual dish surface has been badly damaged, and following more than half-a-century of intensive use it has been decided that it would be too costly and dangerous to try to fix the telescope. Many astronomers and space scientists have been stunned by this decision. (There are numerous other reports on space-related websites, such as here and here, and here, and here, and here; and you might also be interested to follow this Twitter feed: … Read More

Water on the Moon? - Out of Space

Oct 27, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] The space news this week is largely focused on an announcement from NASA regarding the discovery of water on the Moon. Not liquid water – the lunar surface is far too cold for that – but apparently ice deposits in the surface layers in near-polar regions, and perhaps deeper below the surface too. Finding water on the Moon in an accessible form would be important for our future exploration and exploitation of Earth’s natural satellite, perhaps involving permanently-crewed scientific outposts. The water itself would be essential for drinking, washing, and growing food; it could be electrically separated to produce oxygen for breathing; and when split into its constituent hydrogen and oxygen it could be used as rocket fuel. Transporting the necessary water from Earth would be hugely expensive, because we are in a gravity well, … Read More

Science at the movies: The new comet impact film - Out of Space

Oct 22, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Disaster movies forever capture the public attention… but did you ever stop to think that the word disaster actually means bad star? That is, ‘dis’ implies a pejorative (as in disease, or disgust, or disrespect), while ‘aster’ comes from the Latin astrum, similarly the Greek astron. Obviously enough, this derives from old astrological beliefs. In modern science, asteroids are called that because they are star-like (points of light in a telescope), while comets get their name from an ancient Greek word meaning hair-like, referring to the tails exhibited as they cross the night sky. The archetypal disaster movie really should involve an asteroid or comet striking the Earth, then, and there has been no shortage of them. To list a few: Meteor (1979), starring Sean Connery and Natalie Wood (note the pun: starring) Armageddon … Read More

Possible inter-satellite collision on Friday - Out of Space

Oct 14, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Two objects in low-Earth orbit may collide with each other on Friday, in a hyper-velocity impact which would lead to millions of fragments being left on-orbit, each potentially-lethal to functioning satellites. Fingers crossed (not that I am superstitious) that it is a miss, rather than a hit. One local media article is available here. Above I wrote ‘objects’ because neither is an operational satellite. One is Cosmos-2004, a Russian military navigation satellite launched in February 1989, and long past its use-by date. It circles our planet at altitudes between 977 and 1020 km, rather higher than most satellites in so-called low-Earth orbit (LEO); for example, the International Space Station (ISS) orbits at an altitude just above 400 km. If we deserted the ISS, within a few years/a decade or so the tenuous atmospheric drag … Read More

Small asteroid to make near-miss of Earth in NZ skies tonight - Out of Space

Sep 24, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Sorry for the late notice on this one, but I only just heard myself, in common with most of the human race. A small asteroid, somewhere between the size of a truck and the size of a house in dimensions, will hurtle past the Earth tonight, dipping closer to our planet’s surface than the altitude at which TV transmission and weather satellites orbit high above the equator. Not only that, but it seems that it will pass across the sky above New Zealand and Australia, meaning that astronomers here could get the best view during its closest approach, at about 11:18pm NZST. At that time the asteroid would be visible in the constellation Pisces, fairly close to Mars in the sky (the bright reddish object that will rise in the east at about 8:15pm), but … Read More

Tiny asteroid whizzing past Earth today - Out of Space

Jul 28, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] 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 … Read More

The day the sky fell in - Out of Space

Jun 30, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] 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 … Read More

The fate of the albatross - Out of Space

Jun 19, 2020

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] 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, … Read More