- Basic plan of the Milky Way
- Surveying the Galaxy
- Face-on map overview
- Introduction to the Milky Way Explorer
- The Cloud Hunters
- The Star Sweepers
- Things Unseen: The Westerhout radio sources
- The Avedisova catalog: A real Hitchhiker's Guide to the Galaxy?
- Avedisova glossary
- Strange new worlds
- Commentary on the Galactic Plane
- Hydrogen-alpha commentary
- Mapping hydrogen
The purpose of this site is to maintain maps and documentation on the region of the Milky Way galaxy within about ten thousand parsecs (about thirty thousand light years). You can find
- an introduction to this site here,
- the beginning of a collaborative book here including a section on the data sources used to create the map,
- a blog where I occasionally mention changes I've made or plan to make to this site,
- and a twitter feed where I post random thoughts and links.
Please comment here if you happen to drop by. (In order to comment, you have to register by using the link on the left to create an account - it only takes a couple of minutes.) If you are interested in helping out with research or writing, please say so.
You can also email me:
kevinjardine at yahoo.com
Submitted by Kevin Jardine on 10 December, 2012 - 16:02
Patrick Moore, the long serving host of the BBC's astronomy program The Sky at Night has died. I don't remember hearing much about Moore when I lived in Canada, but I certainly did when I moved to Europe and started relying more on the BBC as a source of news. Moore was known as a tireless promoter of amateur astronomy and the public awareness of astronomy, as well as being a harmless eccentric in his political and economic views.
Moore certainly was a tireless promoter of astronomy, but I'm not sure that his political and economic views were either harmless or eccentric. I'll explain below.
As noted by Sarah Kendrew and Phil Plait, Moore was admired and valued by professional astronomers both because his detailed knowledge of the latest science informed his public outreach, and because he inspired a number of his listeners to become professional astronomers during his long career.
I first heard about Moore during the lead up to the solar eclipse of August 11, 1999. Moore spent the eclipse period in Cornwall, seeing nothing, because (as had been projected by weather forecasters) the sky was clouded over. I was puzzled by a BBC interview he did next to a group of disappointed British amateur astronomers in which he expressed sadness at missing the eclipse. I wondered why Moore had not read the weather forecast and gone to southern Germany (as I had - to Augsburg) or further east, where the skies were clear.
I think part of the reason was that Moore was showing solidarity with British amateur astronomers, many of whom lacked the time or money to travel elsewhere. But I think that Moore's unwillingness to travel outside the UK was also a reflection of something larger - a profound nostalgia for a time long ago (before 1950, possibly before 1900) when the English rarely left their island and carried out world class astronomy even in the outskirts of London.
I think that it is this nostalgia for a time when the sun never set on the British empire, when men were men and women stayed at home, that was the root cause of his hostility to the European Union, his support for the UK Independence Party, and his strongly stated views against immigration and better careers for women.
I don't think that this nostalgia was either harmless or eccentric. It was not eccentric, because it is in fact surprisingly common in the UK. While most supporters of the UK Independence Party may not share Moore's views on gender roles, they do share his Little Englander xenophobia and fear of international cooperation, especially through the institutions of the European Union. This nostalgia is not harmless because its prevalence is doing great harm to the UK's international standing, even within the field of astronomy.
The sun now does set on the British empire, and world class astronomy now largely takes place far from England, in the cold dry deserts of Chile, the peaks of volcanoes in Hawaii or in orbiting space telescopes. Even networks of radio telescopes in Europe like EVN require close international cooperation to run.
Most, if not all good science requires expensive instruments and the cooperation of many talented professionals around the world. Without institutions of international cooperation like the European Union, the UK and other European countries would soon be reduced to second class status, falling far behind the United States and (increasingly) China.
Moore's all-too-common political nostalgia was not only bad for the UK's future in an increasingly interdependent world. It was also bad for the practice of astronomy of which Moore was so passionate an advocate. Astronomy is a subject that has no limits and no borders. I hope that its advocates in future will try to have none either.
Submitted by Kevin Jardine on 25 May, 2012 - 16:47
The biggest astronomy news today is not the Dragon docking (though that is a great bit of technology), but the decision to split the giant Square Kilometre Array radio telescope between South Africa and Australia / New Zealand.
The current news stories about this (to its credit, BBC made SKA its lead story) are a bit vague about the implications beyond political buy-in and increasing the cost by about 10%.
The decision was unexpected but is great news for science for at least one major reason: astrometry.
A paper published in 2004 by Ed Fomalont and Mark Reid, Microarcsecond astrometry using the SKA, recommended that the giant radio telescope array be distributed over about 5000 km because such a large radio baseline would allow much more accurate measurements of the positions of the objects it studies.
Splitting SKA between Australia / New Zealand and South Africa produces a baseline even longer than that - more than 10 thousand kilometres.
As explained in this article on parallax, by measuring the tiny shifts in the position of an object in the sky as the Earth orbits the Sun, astronomers can determine its distance.
Distance measurements are essential in mapping the Milky Way and the universe as a whole.
The 2004 article goes on to point out the enormous baselines possible with orbiting radio telescopes (perhaps a 100 thousand kilometres). I suspect that with such huge baselines, astronomers would be able to create 3D maps of many galaxies beyond the Milky Way.
Submitted by Kevin Jardine on 14 March, 2012 - 12:27
Today the first new infrared map of the entire sky in 30 years was released by the WISE team. The previous all-sky infrared map, created by the IRAS satellite in the 1980s, revolutionised astronomy by stripping the veil of obscuring dust away and allowing us to view thousands of objects for the first time.
Since the release of the IRAS data, more detailed infrared observations of a narrow strip surrounding the galactic plane and other selected objects have been carried out by other infrared satellites, including MSX, Spitzer and Herschel. However, much of the sky beyond the galactic plane has been little explored. WISE's sharp view now dramatically improves the previous IRAS results and opens up a huge new opportunity for galactic exploration. This is especially true for local objects within the Gould belt, which can be found anywhere in the sky, but also even in our Milky Way's spiral arms, which are warped and can wander well away from the "official" galactic plane.
Currently the maps are only available in small images appropriate for astronomers studying specific objects. I'll certainly be taking advantage of these to improve the images on this site. In January the WISE team released a breathtaking "supermosaic" of the sky in the direction of Cepheus and Cassiopeia. I hope that the WISE team will be producing more such supermosaics in the future, or perhaps even an interface that allows anyone to explore the entire sky in infrared!
Correction: NASA has released one new supermosaic, an enormous 19080x9598 image of the entire WISE data set. You can find it as the highest resolution version (300MB, below the main image) available here:
Even this enormous image is a tiny fraction of the full WISE data set, but it serves as a useful overview. I'll look into reprojecting it for the Milky Way Explorer on this site.
Submitted by Kevin Jardine on 23 January, 2012 - 09:05
There are many astronomers who have contributed to our knowledge of the Milky Way over the past hundred years but for me one of the most fascinating is Colin Stanley Gum.
Gum is perhaps most famous for his discovery of the Gum Nebula, a vast expanse of nebulosity that may be the closest supernova remnant to our solar system. The Gum nebula is just one of 85 nebular complexes catalogued in Gum's pioneering catalog of HII regions visible in the southern Milky Way. Gum was also an early leader in the field of radio astronomy and his top rate mathematical skills played an important part in determining the exact location and orientation of the galactic plane and centre and in determining the current system of galactic coordinates.
For me, the most fascinating part of Gum's story was his persistence despite a lack of equipment and support from the management of the Stromlo observatory where he worked. His thesis advisor, Clabon "Cla" Walter Allen, left for a new position at University of London Observatory, and the Stromlo director, Richard Woolley, had little interest in his work and at one point even attempted to reject his thesis and deny him a PhD. If it had not been for the intervention of Ben Gascoigne as described here, Woolley might have succeeded in terminating the career of one of Australia's most prominent astronomers.
There are tiny details that suggest a dramatic story but these are mostly tantalising hints. Gum reported that the nebular spectrograph originally used by Gum and Allen was destroyed by one of Stromlo's periodic forest fires, and he was forced to depend entirely upon tiny photographs from a 100 mm (4 inch) Schmidt camera salvaged from the flames. Gascoigne mentioned that Gum "had to go into hospital for medical treatment" after he had written his thesis and there is a reference in a Stromlo history that this was because of a "nervous breakdown". This is a rather vague term. Perhaps it was clinical depression? In any case, Gum was able to recover from the incident and continue his career.
I came across some biographical details today that make Gum's story even more poignant: this genealogical data shows that Gum's father, Stanley Sturt Edgar Gum, died the year his son was born.
Curiously, I have not been able to find a single photograph of Colin Gum on the Internet, but since his father served in the Australian infantry during the first World War, Stanley Sturt Edgar Gum's portrait can be found here.
I wish that someone would write the biography of Colin Gum that he so richly deserves. I think that his enormous achievements despite immense obstacles would be a great inspiration for many young scientists today.
An important part of a Gum biography would be his relationships with the two Stromlo directors during his all-too-short career: Richard Woolley and Bart Bok.
Richard van der Riet Woolley was best known for his sarcastic sense of humour and his sometimes spectacularly bad scientific and technical judgement. In 1947, when asked where he thought radio astronomy would be in 10 years, his response was "forgotten". He also remarked that the idea of space travel was "utter bilge" and wrote that "The whole procedure [of shooting rockets into space]...presents difficulties of so fundamental a nature, that we are forced to dismiss the notion as essentially impracticable".
It is odd that Bart Bok asked Gum's younger colleague Alex Rodgers to lead the effort to create an expanded version of Gum's catalogue, which became the RCW catalogue. Gum's equivalent in the northern hemisphere, Stewart Sharpless, produced an expanded version of his own original catalogue. Why was Gum not asked to do the same? Perhaps Gum himself wanted to move on to other projects? Certainly Bok's respect for Gum's scientific credentials seems clear from Bok's moving obituary for Gum, published after Gum's tragic death in a Swiss skiing accident in 1960.
Submitted by Kevin Jardine on 11 January, 2012 - 08:25
As part of the annual meeting of the American Astronomical Society, NASA released today the most detailed ever infrared image of the Cygnus X region.
The mysterious Cygnus X region is the closest major star formation region to our solar system. It dwarfs the more local star formation regions in the Gould Belt such as Sco OB2 and the Orion molecular clouds. At visual frequencies Cygnus X is obscured by the Rift dust clouds. It was originally detected at radio frequencies and now a team led by Harvard astronomer Joseph Hora has revealed its full glory using infrared images from the Spitzer space telescope.
Hora tells me that astronomer-illustrator Robert Hurt helped to create the image. It is based on data collected before Spitzer ran out of coolant and combines four infrared frequencies.
Up to this point, the most detailed Cygnus X image available was this one from MSX (the Spitzer image is rotated roughly 90 degrees to the MSX image). I'll add the new Spitzer image to the Milky Way Explorer in the near future.
I blogged about the distance to Cygnus X in November 2010 and noted that there was a controversy about whether the objects in this direction are really part of a single region. A recent paper uses radio parallax measurements to establish that there is indeed a single major star formation region in this direction and like our own Gould Belt, it is part of the Orion spur.
The infrared image is centered upon the compact starburst cluster and OB association Cyg OB2, which has created a huge bubble in the interstellar medium. The radio parallax study shows that many other objects in this direction and at a similar distance have motions different from the expanding bubble surrounding Cyg OB2 and so probably developed independently from Cyg OB2 within the same gigantic molecular cloud.
Submitted by Kevin Jardine on 8 December, 2011 - 08:04
Hundreds of new visitors have arrived at Galaxy Map over the past few days looking for a map showing the location of the newly discovered Earth-like planet Kepler-22b and its G5V class parent star Kepler-22. I've never seen this kind of response to a news story before - usually traffic spikes are caused by other sites like Astronomy Picture of the Day linking to Galaxy Map. In this case the traffic spike has come from hundreds of people independently searching for a map.
To meet the demand, I've created a poster derived from several Galaxy Map resources.
The poster is here:
The poster is based on these resources:
Interactive map of the Gould Belt region:
Basic plan of the Milky Way:
Milky Way Explorer:
On the Gould Belt region map, red balls are HII regions of ionised molecular hydrogen gas, green balls are dusty molecular clouds, orange circles are star clusters and the small dots are extremely bright stars (typically supergiants or O and B class hot stars).
Submitted by Kevin Jardine on 17 April, 2011 - 10:39
red = w4
Below is an image of Sh 2-284 I made this morning from the WISE data. The speed of the image server is now reasonably fast - I think the problem yesterday was just that it was down for a while.
I used all four channels, using the equations:
red = w4
green = 0.25*w2+0.75*w3
blue = 0.25*w2+0.75*w1
with a bit of preprocessing of the individual channel FITS files using Aladin first.
I've rotated the image to the right by 90° to compare it with an earlier image I made using Spitzer IRAC and SuperCOSMOS data.
Here's the WISE image:
and here's the earlier Spitzer/SuperCOSMOS image for comparison:
The two obvious differences are that:
- the Spitzer data is higher resolution
- the WISE data reveals more at longer (redder) wavelengths than Spitzer's IRAC instrument. (Spitzer's separate MIPS instrument also covers the longer wavelengths). For this reason the WISE image shows more structure in the interior of Sh 2-284 than IRAC.
It looks like the WISE image server is going to be very useful and I'm looking forward to making more images!
Submitted by Kevin Jardine on 16 April, 2011 - 12:25
The first block of WISE infrared data was released a couple of days ago and there is an explanation of how to access the images here. Unfortunately all that is provided is an (when I tried it) unbearably slow postage stamp image server.
There is nothing like the full pannable and zoomable maps available for other infrared missions such as IRAS or Spitzer GLIMPSE/MIPSGAL. This is a real shame as the WISE all sky data is crying out for a Google Sky like interface.
The first block of data is mostly confined to the inner galaxy with a few key bits of the Gould Belt (Orion/Ophiuchus) and the outer galaxy provided as well. You can see the release map here.
I understand that the lack of a more elaborate interface is partially a funding issue. I hope that some resources become available (Google or Microsoft are you listening?) by the time the full data is released next year.
In the mean time (and if the postage stamp server becomes more responsive) I hope to start doing the Gum/RCW/Sharpless catalog images in infrared.
Submitted by Kevin Jardine on 28 March, 2011 - 16:10
Visitors to this site sometimes ask me about the nearest stars to our Sun. Even the dimmest star shown on the maps on this site is 1400 times brighter than the Sun and most are quite far away.
I've occasionally thought of creating a near star map for fun, but now I see that the RECONS project have done the job for me with this map showing every known star within 10 parsecs:
All that is needed is an overlay to identify each individual star. Hopefully at some point they will add something like that. (I can't because RECONS has released less than half their star data so far.)
There is a much bigger 25 parsecs map (warning slow to load) here: