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sunclock

World map showing the day-night terminator and where the sun is now

What it does

Draws a world map with the illuminated half lit and the dark half shaded, the sun's sub-solar point marked, and the terminator moving in real time. It will also give sunrise, sunset, twilight times and local time for a place you click on, and it ships a set of detailed regional maps.

Why you would want it

Grey-line propagation is the reason. The band conditions along the terminator are different from anywhere else on the planet and the window is short, so knowing where the line is right now -- and which parts of the world it is crossing -- is an operating decision, not decoration. It is also the fastest way to answer "is it dark there yet" before calling.

Before it will work

An X11 session. It draws with plain Xlib and Xpm rather than a toolkit.

How it installs

  • apt: sunclock

Known problems

It is an X11 application from the 1990s and looks like one: no theming, no HiDPI scaling, fixed-size fonts. It works exactly as it always did, and on a 4K display it will be very small. The detailed maps live in a separate package which the main one depends on, so the disk cost is larger than the binary suggests.

Keeping it current

  • probe: apt policy
  • strategy: apt_upgrade

Where to get help with the software itself

Effectively finished software. The GitHub mirror above is the Homepage Debian declares; there is no active development to file against.

Source: catalog/packages/sunclock.yaml