April 29, 2019

Lurking in the shadow, ringing across the Universe: the dark secrets of blackholes

On a bleak December evening in 1915, a German lieutenant scribbled away in his notebook as the World War I raged outside the trench on the Russian front. The barrack reverberated with the noise of war; exploding of shells, shouting of orders, whistles and the cries of wounded men. As he pored over Einstein’s paper, he was more and more incredulous. What his calculation proved was that if any mass is compressed to fit a certain radius, something very strange happens; no known force would stop it from collapsing and nothing would be able to escape that radius. He had found the first exact solutions to Einstein’s equations of general…

March 28, 2019

Music of the Spheres

Humans have been in awe of the harmony of the heavens since times immemorial. Ancient Greeks believed that celestial bodies made music. In the clinging of hammers Pythagoras heard “a clue from God”, or so a folk myth goes. Stretching strings and plucking them, he discovered an intimate connection between mathematics and music, and that objects produced sound when in motion. He was thus convinced that planets moving in orbit should be humming a heavenly tune, and he sought to find the astronomical harmony of the cosmos.   In our modern times, another polymath longed for a similar fulfilment. In 1926 Arthur Eddington, an English astronomer lamented in his book The…

December 21, 2018

The Long Hand of Darkness

Mist lifts over the Boyne Valley in Ireland as the Sun dawns on the stone tomb Newgrange. A narrow sunbeam streams through the passage just above the entrance. It reaches the floor and slowly crawls towards the back of an ancient crossed-shaped chamber. The beam of the rising Sun expands, flooding the tomb of ancestral ashes and bones with light for 17 minutes. This Stone-age alarm announces the 355th day of Earth’s year-long journey around the Sun. Today darkness yawns and stretches over the North, its longest stretch of the year. In a wheat field nearby, Aisling glances up to see the Sun tracing its shortest arc. It hasn’t escaped…

August 3, 2018

Stellar atmospheres and their dietary requirements

stellar spectroscopy

Declaring that I’m an astronomer at social events never fails to cause a sensation. Sat next to a starry-eyed historian at a College dinner last night, he asked: “how do we learn about stars?” as he picked through the salad vegetables on his plate.   Starlight which we observe using telescopes, I said, encodes a wealth of information about the star’s temperature, gravity, and chemical makeup. Telescopes collect parcels of light, called photons, like a bucket collects rain. In1610, Galileo used a simple tube with lenses which he called a spyglass to observe the sky and collect more light than his eyes could. Telescopes have developed a lot since then….

July 17, 2018

The life and fate of our mortal Sun

Today I woke up on the wrong side of the clouds. Having been graced with unusually genial sunshine for more than a month, today looks particularly grim. “Return, alas! return, O radiance dear! And drive from me that foul, consuming Fear” pleads Bradamante in 16th century “Orlando Furioso”. This got me thinking about our 4.6 billion year-old beast and her glittering head. She bewitchingly promises warmth and cheer and when she’s beclouded our moods flop like a wet towel. But what’s going on in that head of hers? At times she scoffs and flares up, spewing fiery flames. She is spotty and certainly has her moods. Last month a scientist even…

July 5, 2018

A journey from your backyard to the stars

Last time you lay down in your backyard gazing at a night sky studded with twinkling lights, could you imagine them being born, living eventful lives then fading away and donating matter back to the Universe, matter which may form new stars and planets one day?   As you lay there, did you wonder why some people spend their lives studying stars?   I’ve been studying them for the past ten years. True story! Tax money pays my salary, so I can’t help but wonder, how does society feel about the stars? Does society even care at all?   If you’re undecided, here are a couple of interesting facts that…

June 28, 2018

Starlight: the muse, compass and human right

Credit: Amanda Smith/IoA

The spectacular splashes of constellations across the heavens have been the muse of story-tellers before humans even learned to write, at times now lost in the mist of history. Around flickering flames and within the ornate walls of the courts of kings, tales were woven around patterns in the stars. The sky then burst with stories of great goddesses and gods, of chained queens, of hunters and heroes suckling on divine milk. Celestial myths are infused with sacred cultural traditions and worldly views of the natural cycles and human condition: plunging into the autumn equinox, toiling throughout the long winter nights and emerging with the rebirth at the spring equinox….