A cheat’s guide to time, space and the Royal Observatory, Greenwich

Before we mosey over to the Royal Observatory, let’s bone up on all the space lingo you’ll need to wax astronomical like a pro while you’re there. All aboard the Vocab Voyager!

1. Light year. No, it isn’t a measure of time. Not even close. But you knew that, right? Right? In fact, a light year is a distance: specifically, the distance light travels through space in a single Earth year. That’s around six trillion miles or, to put it another way, a mind-bogglingly long way. So, when you hear someone opine that e.g. “it’s still light years until payday”, you can make yourself popular by gently but insistently mansplaining their error in cosmic terms.
2. Constellation. No cause for consternation: constellations are merely otherwise unrelated stars over which the childlike human brain has applied join-the-dot pictures. Think Orion the hunter, Cygnus the swan and Cassiopeia the Queen.  The International Astronomical Union currently recognizes 88 of the blighters, each a handy reference point for navigating your way around the night sky.
3. Redshift. Sounds like an episode of Star Trek, and probably is. When stargazers describe the view through their telescopes as ‘redshifted’, it means those galaxies or stars are moving away from us, stretching their light into longer, redder wavelengths. Groovy.

• Right ascension (RA) and declination (DEC). If someone (an old-fashioned aunt, perhaps) wishes to send you a postcard, she’ll use your postcode or zipcode. Want to send a postcard to Mars? Until the Martians give up their home addresses, RA and DEC – effectively the celestial equivalent of longitude and latitude – are your best bet.
• Pulsar. When a massive star explodes it leaves behind a super-dense remnant that spins round and round in space like an oversized galactic disco ball, pulsing out radio waves and light. Don’t forget your flares and sequins.
• Quasar. You can spot these a mile (or – nudge nudge – a light year) off. They’re the dazzling hearts of young galaxies, powered by greedy black holes that are sucking in all the surrounding space matter. Like stars, quasars are so far away that what you're actually looking at is the ancient spectacle of a long-past event.
• The Prime Meridian: Forget about time zones: you’re literally standing at the spot that sets them all. The Prime Meridian (at 0° longitude) runs right through the Royal Observatory and is marked by a stainless steel strip in the courtyard. Set your watch and snap a selfie as you straddle the hemispheres like a colossus.
• GMT. Greenwich Mean Time: the OG standard for international timekeeping. Every clock on the planet sets itself according to this very British idea of punctuality.

No telescope? No problem. If you can hunt out a stargazing spot with minimal light pollution (Greenwich Park is a pretty decent bet), you might just spot a few of our solar system siblings. Planets don’t twinkle like stars, so it’s relatively easy to pick them out, too, once you know what you’re looking for. Hint: a steady light that moves is probably a plane, satellite or alien spacecraft. Here’s your planetary cheat sheet…

• Venus. Our nearest neighbour at a mere 24 million miles away, Venus is the hottest planet in the solar system, with an average surface temperature (465°C) that makes the Costa del Sol feel like Antarctica. Scan the horizon just after sunset to clock this ‘evening star’ – it’s always bright, but especially so in spring and autumn when it’s closest to Earth. Top fact: Venus’s bright lights mean it’s the planet most frequently mistaken for a UFO.
• Jupiter. This gassy behemoth is the largest planet in our solar system by some margin, so it’s pretty hard to miss. Look for a big, bright, steady light, high in the sky, especially during autumn and winter. Top fact: Jupiter’s vast gassy mass is 2.5 times that of all the other planets in our solar system combined. In other words, it’s a whopper.
• Saturn. You can often catch fellow gas giant Saturn hanging out near Jupiter like an annoying kid brother between July and October. But, unless you’re blessed with Superman vision, you’ll need a very good set of binoculars to glimpse the famous rings. Top fact: Saturn is the only planet in our solar system that’s less dense than water, meaning that – technically – it would bob back up to the surface if submerged in a sea big enough.
• Mars. The Red Planet’s pinky-orange glow makes it fairly easy to pick out in the night sky, even though it’s only about half the size of Earth. Top fact: Mars’s Olympus Mons volcano is the loftiest peak in the solar system, at a dizzying 13 miles high.
• Mercury. Blink and you’ll miss it: Mercury’s proximity to the sun means it’s only very briefly visible above the horizon. Try just after sunset or just before sunrise in April and October for the win. Top fact: Mercury’s rotation (59 Earth days) is so slow, and its orbit of the sun (88 Earth days) so fast, that only 1.5 days pass in every Mercury year. Do they even bother with months there? Probably not.

Burn brighter than a quasar and impress friends with your space savvy thanks to these Royal Observatory trivia tidbits…

• The Royal Observatory was commissioned by stargazing enthusiast and ‘Merry Monarch’ Charles II in 1675. 
• Almost as inevitably as the daily rotation of this planet we call Earth, the observatory was designed by architect-in-chief Sir Christopher Wren. Coincidentally, Wren was also once a professor of astronomy at Oxford. Was there anything that man couldn’t do?
• John Flamsteed was appointed as the observatory’s first Astronomer Royal, serving from 1675 until his death in 1719, and the main observatory building is named after him (for the sake of clarity it’s called Flamsteed House, not ‘John’). Flamsteed was best-known for his epic Hogwarts-esque book of stars, the ‘Stellarum Inerrantium Catalogus Britannicus’, and for being one of the earliest astronomers to set hungry eyes upon Uranus. Stop sniggering at the back!
• Other famous astronomers to be closely associated with the observatory include Edmond Halley (of comet fame), Isaac Newton (of gravity/apple renown), and Frank Dyson, who had nothing to do with vacuum cleaners and everything to do with the invention of that earworm audio time signal – ‘the pips’.
• The Royal Observatory is also where horologist extraordinaire John Harrison cracked the nautical longitude code with his pioneering marine chronometer, and has been the location of the planet’s Prime Meridian line since 1851.

1. H4. Before smartphones, we had wristwatches and, before wristwatches, pocket fobs. Time-travel back to 1759 for a peek at John Harrison’s pioneering longitudinal pocket chronometer, H4, the 18th-century seafarer’s navigational timepiece of choice. Drop this fact: though H4 made Harrison rich, political back-stabbing and goalpost-shifting meant he never received the full £20,000 (nearly £4m in today’s money) originally promised by the far-more-interesting-than-it-sounds Board of Longitude.
2. Great Equatorial Telescope. Housed inside the Great Equatorial Dome, this 28-foot-long monster boasts a 28-inch lens, making it the largest telescope of its kind in the UK. Drop this fact: the observatory’s famous ‘onion dome’ was added in the 1890s to accommodate the telescope.
3. F.M. Fedchenko clock. This fine pendulum clock was developed in the middle of the 20th Century and is said to be one of the most accurate timepieces of its kind on the planet. Drop this fact: the clock averages only 0.002 seconds of error per day, meaning it would take 80 years – give or take – to lose a minute. 
4. The Time Ball. Not the most imaginative name, to be sure, but it does what it says on the tin. Set your watch by the tomato-red ball that drops every day – like clockwork, if you will – at 1PM, allowing mariners (and everyone else) who sees it to accurately set their chronometers, watches and clocks from afar. Drop this fact: the ball drop has been triggered by electrical impulse from the 24-hour Shepherd Gate clock since 1852, and prior to that by a manually operated (and surely far more error-prone) rope and pulley system.
5. The Prime Meridian. Here’s where, at Longitude 0, time is standardised for the whole planet and where you can enjoy the uniquely trippy experience of standing simultaneously in both the east and west hemispheres. Drop this fact: before GMT, there was no standardised method for measuring time – back then, most people just squinted at the sun and made an educated guess.

And there you have it! Our bluffer’s guide to time, space and the Royal Observatory, Greenwich. Now you’re all set to blow your friends’ minds with that famous intergalactic intellect of yours. But what else do you need? Why, The London Pass®, of course! Head over here to secure entry to the Royal Observatory and over 100 more top London attractions.

Add some extra gravitas to your Greenwich adventure by casually dropping one (or more) of these literary lines while strolling the Royal Observatory. Bonus points if you can successfully pass them off as your own…

“We are all in the gutter, but some of us are looking at the stars.” – Oscar Wilde

“Time travels at different speeds for different people.” – William Shakespeare

“The cosmos is within us. We are made of star-stuff.” – Carl Sagan

“Remember to look up at the stars and not down at your feet.” – Stephen Hawking

“Time is an illusion. Lunchtime, doubly so.” – Douglas Adams