Archive for the 'Science' Category

[Stellar Mapping] The 2300AD Near Star Map

The 2300AD Near Star Map

The 2300AD RPG – originally published by Game Designer’s Workshop in 1988 – presented an excellent gritty, realistic near-future hard sci-fi setting with lots of exploration, mystery, and interesting aliens. It’s also about to be republished by Mongoose Publishing as a setting for their version of the Traveller RPG!

One of 2300AD’s most interesting features is that the setting is built around a realistic (for the 1980s) Near Star List based on the Gliese Catalogue (2nd Version). FTL travel in 2300AD has a maximum range of 7.7 lightyears, resulting in the creation of “Arms” that extend from Sol to connect only the stars that are within this range of eachother (this limit can potentially be extended to 11.55 ly using Stutterwarp tugs, but this is expensive and uncommon).

There are three of these Arms, each colonised by a different political power in the setting – the French Arm, the Chinese Arm, and the American Arm. The French Arm stretches “upwards” from Sol towards Galactic North, ending at the orange giant star Arcturus. The American and Chinese Arms share the same beginning, but split off so that the American Arm heads Coreward/Spinward while the Chinese Arm sprawls around the (galactic) southern part of the solar neighbourhood.

Unfortunately the Near Star List (NSL) has not been updated for the new version of 2300AD. A lot of stars have been discovered in the solar neighbourhood since the late 1980s (as shown on my Stellar Mapping page), and the locations and distances of existing stars have been greatly refined since then too – so how does the updated stellar data affect the Arms?
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[Stellar Mapping] RECONS list updated!

Oops! Gliese 667 slipped through the cracks and wasn’t included in any of the original stellar datasets on my Stellar Mapping page! This is slightly embarrassing since it’s a bit famous for having planets around it! It was within 22.8 ly from Sol, but for some reason wasn’t on the RECONS list – and because it was so close it wasn’t included in the Hipparcos dataset either.

I’ve now added Gliese 667 to the RECONS CSV files, so if you’ve already downloaded the RECONS data, you’ll need to download the new version so you can include Gliese 667! (I only found it because I was checking the stars on the American Arm for 2300AD!). There shouldn’t be any other missing stars there – I checked the border between RECONS and HIP and couldn’t find any other HIP stars within 22.8 ly that weren’t already on the RECONS list.

[Stellar Mapping] How to make your own stellar database!

Looks like my new Stellar Mapping page has been well received so far – thanks to everyone who has shown an interest in it, I hope you’re finding it useful!

In this article I’m going to show you how to make your own stellar database, with the same tools I used to construct the ones I presented on my mapping page. For this exercise we’ll be relying on something called VizieR, which is a huge online database of thousands of star catalogues. You’ll need to have a basic understanding astronomy to make the most out of this, but it’s not that tricky.

Let’s say you want to make a database of stars in a corridor between Sol and the famous Pleiades star cluster (if you’re familiar with the 2300AD RPG, this is essentially the path the Bayern took to the Pleiades). We’ll be using the Hipparcos star catalogue, since it has the most accurate parallax measurements (from which we can derive distances).

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Website Update: Stellar Mapping page updated!

My new Stellar Mapping page is finally online! This is a complete rewrite of my previous “Realistic Astrography” page, and now includes Equatorial to Galactic co-ordinate conversion files, the complete RECONS (2012) and DENSE star lists, as well as all the data from the Hipparcos, Gliese 3, and Yale catalogues for stars out to 300ly from Sol! And the Further Stars list is also in there too :)

RECONS-coreward

RECONS dataset, looking towards the galactic core.

The focus has moved away from Traveller and its hex map format (I realised that I was taking accurate data and then making it inaccurate by forcing it into hex map format, so I’ve dropped that completely) and moved towards raw data and Astrosynthesis, but this will still be very useful for anyone interested in using realistic data for the stars near Sol.

You can check it out at http://evildrganymede.net/rpgs/stellar-mapping/

I’ll be writing some articles in the coming weeks to expand this – this will include how to use the Vizier stellar databases, and what this means for the 2300AD RPG!

Website update: Further Stars List uploaded!

EDIT: This has been superseded by my new Stellar Mapping page!

I’ve finally added the “Further Star List” to my Realistic Near-Sol Astrography webpage – it’s an excel file containing accurate locations of a selection of major stars (including Vega, Deneb, 51 Pegasi, Spica, Bellatrix and Algol) that are more than 10pc from Sol.

The format is a bit raw (and I’m not entirely sure why I selected those specific stars to list!). The dark red X/Y/Z columns show the distances in each direction (Sol is the origin, +X is Coreward, +Y is Spinward, +Z is “above” Sol). If you have trouble interpreting it, let me know!

You can doublecheck the stars too – you can use the Convert spreadsheet in Section 1 of the mapping page to convert the RA/Dec of any stars into X/Y/Z coordinates. If you have astronomy software like Celestia, open it up and activate the Galactic Grid and rotate it so that you’re facing 0° latitude and 0° longitude – you’re now looking directly along the +X axis. Turn to look at 0° Lat, 90° Lon and you’re looking directly along the +Y axis. Look at the Galactic north pole, and you’re looking directly along the +Z axis. You should be able to find your stars using this (e.g. Aldebaran is pretty much directly along the -X direction, and down a bit on the Z axis. Look towards 180° Lon direction and -20° Lat, and there it is!).

I’ve been sitting on this for six and a half years (!!) and finally decided that I’m never going to draw hexmaps showing these stars, so I may as well just release the data and let other people figure it out! Enjoy! :)

The link is at http://evildrganymede.net/rpgs/stellar-mapping/.

The Journey Home

Whatever you’re doing today, find some time to watch this – it’s astronaut Ron Garan’s amazing timelapse video of the Earth seen from the International Space Station as it hurtles around our world every 90 minutes. There are all sorts of wonders in here – lightning, cities, aurorae, stars, and even the moon makes an appearance – plus it has an awesome soundtrack! :)

Time Lapse From Space – Literally. The Journey Home. from Fragile Oasis on Vimeo.

(more info at http://www.universetoday.com/91170/ron-garans-incredible-iss-timelapse-coming-back-home/ )

Dawn arrives at Vesta!

(I was going to call this post “Dawn breaks at Vesta” but that might have given the false impression that Dawn literally broke in orbit and isn’t working anymore ;) )

Dawn successfully entered Vesta orbit in the weekend, and has returned the first pictures from Vesta orbit!

Vesta! (Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

The big lump in the middle of the asteroid is actually the central peak of a massive crater caused by an impact that literally blew away most of the protoplanet’s southern hemisphere! There are all sorts of interesting things to see here – lots of bowl-shaped craters, grooved/scallopped terrain in the big crater floor, and what looks like a huge cliff marking part of the rim of the big crater!

There’s also a very nice image showing another view of Vesta’s ‘south pole crater’, along with other asteroids that we’ve sent spacecraft to shown to the same scale:

Vesta, with other asteroids (Image credit: NASA/JPL-Caltech/JAXA/ESA)

Vesta is about 530 km in diameter, so it’s pretty large for an asteroid – it’s the third largest in the asteroid belt – and is far bigger than Lutetia, which was previously the record holder for ‘largest asteroid visited by a spacecraft’. Dawn will move on to visit Ceres next year, which is the largest asteroid in the asteroid belt and (unlike Vesta) is actually spherical too.

We’ll see more of Vesta as Dawn maps it from orbit over the next year – this only the beginning, and I’m very excited to see what else will be revealed! (You can find out more about the Dawn mission at its official website)

Approaching Vesta!

Vesta! Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

On July 15th, NASA’s Dawn spacecraft will be entering orbit around the asteroid Vesta – and I’m really looking forward to it! This is a new frontier – while we’ve seen a few small asteroids (e.g. Ida, Gaspra), we’ve never seen a big asteroid up close, and Vesta is the third largest asteroid in the asteroid belt between Mars and Jupiter (it’s also the second most-massive after Ceres, which will be visited later by Dawn). We’ve also found several meteorites on Earth that we think were blasted off from Vesta’s surface by impacts on the asteroid – these indicate that Vesta should have differentiated into a rocky mantle and metallic core, and I’m curious to see if there is evidence of volcanic activity on its surface (my Ph.D. supervisor published some papers about Vesta’s early history, and some of his interest and enthusiasm about it has rubbed off on me!).

Asteroids are interesting beasts – they’re mostly found in the space between Mars and Jupiter, and are remnants from the formation of the solar system. The rocky planets in the solar system formed by accretion in the solar nebula about 4.6 billion years ago – put very simply, dust grains clumped together due to gravity to form planetesimals, which themselves clumped together to form protoplanets, which then clumped together to form larger planets. However, Jupiter’s gravity affected (and still affects) the orbits of nearby objects, which prevented the asteroids from accreting into planets. As a result of this, we now have a band of asteroids between Mars and Jupiter – it’s essentially debris that was never allowed to form into a planet. What’s more, if you could combine all the asteroids currently in the asteroid belt, the resulting object would be smaller than our own moon (part of this is due to the fact that many asteroids have been ejected from the belt by gravitational interactions or destroyed by collisions)! Since we’ve not seen a large one up close before, a lot of planetary scientists will be interested to see what Dawn reveals at Vesta (and later when it moves on to orbit Ceres, which is the largest asteroid and also a dwarf planet).

As Dawn has been approaching Vesta over the past few weeks, features have been slowly coming into view that we couldn’t see from Earth. The latest picture (shown above) hints at interesting features – for one thing, there don’t appear to be an awful lot of large craters visible, which would imply that its surface may be young (possibly evidence for volcanic resurfacing?). Some curvilinear features are also visible in the southern hemisphere – maybe they’re tectonic in origin, or perhaps they’re something else (crater-chains? flow fronts?). Right now it’s all very tantalising, but we’ll find out more when Dawn goes into orbit in a few days!

[Book Review] The Demon-Haunted World, by Carl Sagan

Demon-Haunted_WorldSummary: If everyone read and understood this book, the world would be a much more sensible place. It should be required reading for everyone, whether they’re interested in science or not.

Review: The Demon-Haunted World: Science as a candle in the dark is in my opinon one of the Carl Sagan’s most important works. In it, Dr Sagan does nothing less than explain how science works, and provides a clear framework for readers to understand how to view the world rationally and skeptically.

While the internet is potentially a veritable goldmine of information, nowadays it is a double-edged sword. On the one hand, it’s a great resource for research and learning about the world if you know how to look for relevant material and how to assess it and filter out what you don’t want or need. On the other hand, there’s a lot of noise to wade through, consisting of wacko pseudo-science, crazy conspiracies and New Age ideas like the end of the world in 2012, Nibiru, faked moon landings, “Intelligent Design”, religious raptures, magic healing rocks, crop circles, “energy healing” and other such nonsense. Much of this is presented “authoratively” and if a reader doesn’t know better – or doesn’t know how to question these ideas – then it’s not surprising that people can be taken in by them.

While many of these ideas gained popularity after the book was first published in 1996, The Demon-Haunted World is aimed at addressing this problem. Thematically, the book is divided into three parts – the first few chapters present some of the pseudoscience ideas (those prevalent during the 1990s, at least) and debunks them by discussing them skeptically and presenting reasoned scientific arguments against them. The second part – the meat of the book – presents the “Baloney Detection Kit”, which describes how science works and how to think logically and skeptically about what you’re presented with in order to determine an idea’s validity. Can the idea be tested? Can the facts be confirmed independently? What happens if the idea is extrapolated beyond its initial statement, etc? This is an invaluable manual for honing one’s critical thinking skills – something that sadly doesn’t seem to be taught much as a specific subject at schools and universities, and seems to be very much lacking in the world today. The final part of the book is more a collection of essays related to the theme of science communication, the standard of science education in the US, and freedom of expression (with a bit of politics thrown in) – not directly relevant to the rest of the book perhaps, but still an interesting read.

Science is presented as a “light” that shines against this oncoming “darkness” – dramatically put perhaps, but I do genuinely think that there is a real danger that scientific ideas are slowly being cast aside in favour of superstitious nonsense. Already we have had politicians with “faith-based policies”, “alternative medicine” touted as being superior to real medicine without clinical trials or peer-reviewed studies, and pseudoscientific garbage against evolution presented as a valid alternative in school science classes. Is this really where we want to be in the 21st Century? I don’t think so, and I fully believe that these ideas should be actively fought against wherever they may arise.

The Demon-Haunted World most likely won’t convince people who are already hardcore believers in pseudoscience of the fallacy of their ideas – they’re probably too far gone for that – but it can at least be used to immunise others against their ideas. It provides a very useful mental toolkit, not only when it comes to understanding science but also for constructing a rational view of the world in general. As such, I think everyone needs to read this book!

Still alive

Well, I’m still here. So, apparently, is everyone else. Earthquakes, tidal waves, Great Beast Dagon rising, people ascending to heaven, etc etc didn’t happen. I particularly appreciated the inspired elegance of Eternal Earthbound Pets, an atheist-run company set up to look after the pets of people who have been “taken to heaven” in the Rapture (no refunds of course! And being atheists, they’d definitely be left behind so you know they’ll be there to take care of your beloved animal companions! Genius! ;) ).

On a more serious note, science educator Neil deGrasse Tyson raised an interesting point on Twitter today – “If Jesus actually arrives May 21, it’ll be easy to convince skeptics. If he doesn’t show up, do the faithful become atheists?

It’d be nice to think that they would… but I suspect that people who genuinely believed that they’d be “taken to heaven” are already so far gone from rational thought that they’d just come up with excuses like how their faith has been “tested”, or that human error in calculating the date was to blame and that the Rapture would still happen at a later date, and just keep on believing (in some cases, because their faith is literally all they have now). I’ve even seen people ‘correcting’ the Rapture-believers by saying that the bible says that “no man will know the date”, but that doesn’t get around the fundamental problem that they’re believing a work of fiction that has no basis in reality to start with! Irrationality is funny like that.

EDIT: Yep. The “believers” interviewed in this article from The Independent are all making excuses rather than abandoning their faith. Typical.

I guess the next scheduled “end of the world as we know it” will be the Mayan Apocalypse in December 2012, so we have about 18 months to prepare for the next bout of insanity to sweep the world (and IMO that one’s even crazier than the Rapture). And I wonder why I sometimes feel I’m fighting a losing battle to educate people about science… I think I’ll go hug my copy of “The Demon Haunted World” by Carl Sagan now (which I would say is required reading for everyone).