Vanuatu!

I’m off soon to Vanuatu for a holiday. Above (click to zoom) is a map of this island nation (produced using the raster package of R, with my own colour palette). The map outlines are from gadm.org (which is missing an island, unfortunately). Elevation data is from the Shuttle Radar Topography Mission (with additional void fill using a lower-resolution dataset).

The overlay in red shows light visible at night (from NASA’s Earth at Night). Apart from the two main towns of Luganville and Port Vila, the active volcanoes on Ambrym and Tanna are clearly visible (take a closer look at Ambrym’s lava lake here).

Not highlighted is the active volcano on Ambae, an island which held 4% of the nation’s population until it was recently evacuated – consider helping the evacuees via Anglican Aid.


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Australian plant families revisited

This visualisation (revising an older post) shows the sizes of major Australian plant families, compared to world totals (based on slightly old data from here).

Australia’s 836 orchid species are only 3% of the world total, but Australia has 89% of the Goodeniaceae.

Plants illustrated include the Golden Wattle and Sturt’s Desert Pea.


The Seasons

It’s solstice time in a few days, so here is an infographic on the seasons (click for hi-res image):

Infographic constructed using R (with DescTools::DrawCircle, rasterImage, layout, and the suncalc package for day length calculation). Images used are a diagram by “Colivine,” paintings by Arthur Streeton and Joseph Farquharson, and two photographs of my own.


The constellation Scorpius

Winter is here (in the Southern Hemisphere, at least), and the constellation Scorpius always heralds the southern winter’s icy sting. The image below is based on a vintage astronomical illustration, but I have corrected the star positions of the major stars and indicated their apparent magnitude (brightness) and approximate colour (based on spectral class). It is interesting to compare the image with this quality photograph.

Generations of astronomers have memorised the O–B–A–F–G–K–M stellar classification system developed by Annie Jump Cannon with the mnemonic “Oh, Be A Fine Girl/Guy/Gal/Gentleman, Kiss Me.” Scorpius does not contain any bright O-class stars, but it is easy to see stars ranging from the hot blue-white B class to the cooler orange-red M class (stars which are only “red hot”).

The most obvious star in Scorpius is the enormous red supergiant Antares, which has that name because it is easily confused with the planet Mars (Ares). It is also known as “Cor Scorpii” (the heart of the scorpion). It is easy to recognise the curved tail as well, with the stingers Shaula and Lesath at its tip. It is less obvious which stars are the scorpion’s claws – the artist here has drawn the left claw extended so as to reach the dim white star Psi Scorpii. Other artists draw the scorpion facing more to the right, with the line of blue-white stars being the claws.

Infographic constructed using R (with lm to map true sky coordinates to image coordinates, rasterImage for the background, and the showtext package for fonts).