Top five
November/December 2025
NIGHT LIGHTS
Stewart Langdown on star gazing and celestial phenomena
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rowing up in the era of the Moon landings, the Space Shuttle and the International Space Station, my fascination with the night sky only deepened. As an amateur astronomer, I've explored it both with the naked eye under very dark skies and through my own telescope. It’s amazing to think our ancestors gazed on these same stars, mapping their movements to navigate and tell stories. Phenomena such as comets, meteors and solar eclipses must have seemed like pure magic. Early mankind even tracked the seasonal changes and equinoxes to manage their lives. To consider that some starlight began its journey toward Earth before the dinosaurs walked the planet is a truly humbling thought. Stewart Langdown, FSLL, is director of business development at Zencontrol and member of the SLL marketing and communications committee
3 The Great Equatorial Telescope The Great Equatorial Telescope (28-inch refractor) was pivotal in advancing astrophysics at Greenwich. Installed in 1893, its primary purpose became the meticulous observation and measurement of 'double stars' (binary systems). By tracking the changing angular separation and position of these star pairs over decades, astronomers could calculate their orbital paths and masses, which was crucial for understanding their nature.
X: @sll100
1 The Greenwich Meridian The Greenwich Meridian, or Prime Meridian (0 degrees longitude), is the imaginary line established in 1884 at the Royal Observatory in Greenwich, London. It is the globally accepted reference point for calculating time zones and East/West positions. A powerful green laser light beam, installed in 1999, permanently marks its location. Every night, this beam shoots out precisely along the meridian from the Observatory, extending into the northern sky, visually signifying the starting line for global time and space.
4 The Andromeda Galaxy The Andromeda Galaxy (M31) is the nearest major galaxy to our own Milky Way, located around 2.5 million light-years away in the Andromeda constellation. The largest member of our Local Group, this barred spiral galaxy spans 152,000 light-years in diameter and has some one trillion stars. It is a dominant presence, visible to the naked eye under dark skies. Notably, it exhibits a significant blueshift, indicating it is approaching the Milky Way, with a galactic collision predicted in around 4.5 billion years.
2 Royal Observatory The light pollution from the expanding London metropolis severely hampered the ability of the Royal Observatory at Greenwich to conduct astronomical research. The increased sky glow, along with general air pollution, reduced the visibility and quality of celestial observations. This deterioration in observational conditions was a key factor in the relocation of the main astronomical and magnetic departments of the Royal Observatory out of Greenwich to the darker site of Herstmonceux, Sussex, a process beginning in 1947.
5 The Moon The Moon is crucial in measuring seasons primarily through its role in calendars. Its easily observable phases – the lunar cycle of approximately 29.5 days – provided the earliest, most reliable unit of time longer than a day. Many ancient societies, such as the Babylonians, created lunisolar calendars that used lunar months but required periodic 'leap months' to keep the calendar year synchronised with the solar year, and thus the agricultural seasons.
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