About In-The-Sky.org

In-The-Sky.org is an online guide to what you can see in the night sky, automatically tailored to wherever you happen to live on Earth.

Founded by Dominic Ford in 2012, it has grown to cover planets, asteroids, comets, deep sky objects, as well as satellites in low-Earth orbit. The site now includes an extensive searchable catalogue of astronomical events spanning the years from 1950 to 2300.

How it works

In-The-Sky.org needs to know where you live to work out what you can see in the night sky. By default, it traces where your internet connection is coming from, but sometimes this doesn't work out. If you want to manually specify where you live, then click here.

Once we've got your location, we need to calculate where objects will appear in your sky. Most of our planetary predictions are derived from the DE430 ephemeris, which is produced by NASA's Jet Propulsion Laboratory (JPL) in California. NASA use this to guide their space missions to their intended destinations, so it is astonishingly accurate, typically listing the positions of the planets to an accuracy of a few kilometers.

To list the eclipses, conjunctions, oppositions, and other such alignments that you'll be able to see, we do an automated search of DE430 for events which seem favourable. Much of the text you'll see on In-The-Sky.org is automatically generated specifically for you, based on exactly where in the sky each event will appear.

The positions of asteroids are calculated from orbital elements published by Ted Bowell of the Lowell Observatory. Orbital elements for comets are taken from the Minor Planet Center (MPC). Comet magnitudes are calculated on the basis of observations sent into the BAA Comet Section. The positions and brightnesses of deep sky objects are taken from a wide variety of catalogues.

Much of the science behind how In-The-Sky.org does its calculations is described in the author's book, The Observer's Guide to Planetary Motion , published by Springer.

Dominic Ford

Dominic Ford

I work at the Institute of Astronomy, Cambridge UK, as a software developer on the European Space Agency's PLATO mission. We are responsible for developing the PLATO exoplanet search pipeline, which will become operational when the spacecraft launches in 2026.

I previously led the development of the data-analysis pipeline for 4MOST's spectroscopic surveys of the Milky Way, working in Sofia Feltzing's group at Lund Observatory, Sweden (2017–2019). 4MOST will observe the spectra of tens of thousands of astronomical targets every night, generating a volume of data that poses unique challenges. Machine-learning techniques are likely to offer the only affordable way to analyse such a large dataset, but the interpretation of their output requires care.

In my spare time, I work on many science communication and amateur astronomy projects. In 2022, I was awarded the British Astronomical Association's Horace Dall Medal for the development of software systems to benefit amateur astronomers.

Amateur astronomy projects
  • In-The-Sky.org – A guide to what's visible in the night sky, automatically tailored to wherever you happen to live on Earth. As well as a planetarium and charts/tables for individual objects, the site has now grown to include an extensive searchable catalogue of astronomical events spanning the years from 1950 to 2300.
  • Astrophotography archive – A searchable online database of amateur astronomical images, developed in collaboration with the British Astronomical Association.

    As of December 2022, the archive contains over 65,000 images, searchable by object, object type, date, etc. The BAA's archives go back many decades and we are working to digitise many of the older images and glass plates, with the aim of documenting how amateur astronomy has changed through the 20th century.

    In addition to the BAA's archive, I also maintain a much smaller personal archive of my own astrophotography.

  • Pi Gazing – A fun project to create a network of motion-sensitive cameras which record shooting stars, satellites, aircraft, and anything else in the sky that moves. When the same object is spotted simultaneously from multiple observing sites, its three-dimensional trajectory can be triangulated.

    I use off-the-shelf security cameras, with Raspberry Pi computers housed in the camera enclosures to do real-time analysis on the images. Each observatory is highly autonomous, using astrometry.net to precisely determine the sky area that each camera is pointing at, and a GPS receiver to determine the camera's location.

    This project ran from 2014–2016 in collaboration with Cambridge Science Centre under its former name of MeteorPi. Between 2020–2022, the project observed again under its new name of Pi Gazing. The code is all freely available on GitHub.

Other web-development projects

A more complete archive of my amateur software-development projects can be found on GitHub.

  • ScienceDemos.org.uk – A collection of fun interactive online science demos, implemented in Javascript.
  • JSPlot – An open-source Javascript graph-plotting and vector-graphics library, designed for embedding scientific charts in websites. I use this library extensively throughout the websites I maintain.
  • HillTopViews.org.uk – A three-dimensional interactive terrain map of the Earth and Moon. The Earth maps are based on altitude data collected by NASA's Shuttle Radar Topography Mission (SRTM) in 2000, combined with additional open-source data from Open Street Map. The Moon maps are based on a digital elevation model (DEM) from the Lunar Orbiter Laser Altimeter (LOLA; Smith et al., 2010), an instrument on the NASA Lunar Reconnaissance Orbiter (LRO) spacecraft (Tooley et al., 2010).

    In both cases, the data is displayed using a custom-built three-dimensional Javascript rendering engine.

  • Retrocomputing archive – In the 1980s and 1990s, I learnt to program using 8-bit Acorn and Commodore computers. Here you can find a preserved archive of files recovered from cassette tapes and floppy disks from that era.
  • Dominic's photos – When I'm not doing other things, I dabble in amateur photography. You can find some of my photos here.
  • Family photos – An archive of around 5,000 old family photos, going back to the 1950s (password protected).
Older projects
  • The Observer's Guide to Planetary Motion – My book, which describes much of the science behind how In-The-Sky.org does its calculations.
  • Pyxplot – A graphing and vector graphics package which I wrote in 2008–2012.
  • GrepNova – An automated image-comparison tool which I wrote in 2005 for amateur astronomers who hunt for supernova. This tool was used by Tom Boles, who currently holds the world record for the largest number of supernovae discovered by any single individual.
  • Naked Astronomy – Between 2012 and 2014 I worked for the Naked Scientists in Cambridge, where I produced the monthly STFC-funded podcast Naked Astronomy. I also spent one day a week in the newsroom of BBC Radio Cambridgeshire, acting as a science advisor.
  • Square Kilometre Array – Between 2007 and 2012, I worked at the Cavendish Laboratory, Cambridge, on feasibility studies for the use of Graphics Processing Units (GPUs) to build a correlator for the SKA.
  • PhD Thesis – I was awarded my PhD from the University of Cambridge in 2008, where my supervisor was Prof Paul Alexander. I built a model of the infrared spectra of dusty star-forming galaxies, which were being observed in large numbers at that time by Spitzer.
Ancient projects

In the 1990s I was the kind of geeky teenager who sat in my bedroom writing computer games for my Acorn Electron. I even got a couple of them published. Though the reviewers spotted, quite correctly, that I wasn't very good at making up story lines.

  • Shipwrecked – Published here (1996) and reviewed in detail here. In the unlikely event you want to try and complete it, you may find this solution useful. It even got ported to the Commodore 64 and some YouTubers have recently made some videos about it (!!).
  • Jupiter III – The sequel to Shipwrecked, published here (1996) and reviewed in detail here. This was my first attempt at high-speed scrolling graphics. In the unlikely event you want to try and complete it, you may find this solution useful.

All of the information and diagrams on this website are © Dominic Ford.

However, they are provided for the benefit of amateur astronomers worldwide, and you are welcome to modify and/or redistribute any of the material on this website, under the following conditions:

  1. Any item that has an associated copyright text must include that unmodified text in your redistributed version,
  2. You must credit me, Dominic Ford, as the original author and copyright holder,
  3. You may not derive any profit from your reproduction of material on this website, unless you are a registered charity whose express aim is the advancement of astronomical science, or you have the written permission of the author.

Contact details

You can email me at .



San Diego



Color scheme