Science: Stars and Planets: March

OUR MILKY Way galaxy is populated not just with stars and planets made of ordinary matter, but with worlds made of a strange kind of "mirror matter" that we cannot see. This startling new theory links together experiments in particle physics and measurements of gravitational force in the Universe - and it suggests that aliens could be living much closer to us than we might suspect.

The starting point is evidence that our Galaxy has an unexpectedly strong gravitational pull - more powerful than we would expect from the visible stars and gas making up the Milky Way. It must contain some kind of "dark matter" that has a gravitational pull but is not obvious to any telescope.

Astronomers in Australia and Chile are on the track of this dark matter. They have found that the stars in a neighbouring galaxy, the Large Magellanic Cloud, sometimes seem to brighten unexpectedly. Most likely, their light is being focused by the gravity of objects in the outer part - the halo - of the Milky Way. These objects are called Machos - massive compact halo objects - and they weigh about half as much as the Sun.

Machos cannot be ordinary stars, because they don't emit any detectable amount of light. Most astronomers think that they are some kind of shrunken star - a white dwarf, a neutron star or a black hole. But Rabindra Mohapatra and Vigdor Teplitz, of the University of Maryland have a new idea, rooted in particle physics. There is now a lot of evidence that the light particles called neutrinos can change from one type into another. The results are best fitted if the neutrinos first change into a different kind of matter altogether - so-called "mirror matter" - and then back into another neutrino.

The mirror-world has a counterpart for each of the particles making up the Universe we see, such as the proton and the electron, but - the Maryland physicists calculate - the mirror-particle would weigh only one-twentieth as much. Whereas ordinary heavyweight stars in our Galaxy weigh about 10 times as much as the Sun, the heaviest "mirror stars" would weigh half of the Sun's mass.

Mohapatra and Teplitz realised that is just about the mass of the Machos in our Galaxy. Mirror-stars fit the bill for Machos in another way, too. They would not be visible, because they produce "mirror-light" that can't be detected with an ordinary telescope. .

Mohapatra believes that the mirror-stars could easily have mirror-planets and on these worlds life may have arisen. These aliens cannot see us, any more than we can see them.

What's up this month

Early March is a good time for Mercury-spotting. On March 3, it sets over an hour after sunset at about 7.30pm, before turning tail and plunging back sunwards by mid-month. Its fellow inner planet, Venus, is also visible in sunset skies, growing even brighter and setting three hours after the Sun.

Mars is beginning to put an appearance in our evening skies again, rising about 10pm mid-month. The stars now on view tell us that Spring is on the way. Replacing the winter constellations at centre-stage are the spring constellations of Cancer and Leo - the latter being one of the most ancient star-patterns of all, and one which really does resemble its namesake, the lion.

Heather Couper and

Have you tried new the Independent Digital Edition apps?
Arts and Entertainment

ebooksNow available in paperback
Arts and Entertainment

ebooks
Arts and Entertainment

film
Arts and Entertainment
Chvrches lead singer Lauren Mayberry in the band's new video 'Leave a Trace'

music
Arts and Entertainment

music
Arts and Entertainment
Home on the raunch: George Bisset (Aneurin Barnard), Lady Seymour Worsley (Natalie Dormer) and Richard Worsley (Shaun Evans)

TV review
Arts and Entertainment

TV
Arts and Entertainment
Strictly Come Dancing was watched by 6.9m viewers

Strictly
Arts and Entertainment
NWA biopic Straight Outta Compton

film
Arts and Entertainment
Natalie Dormer as Margaery Tyrell and Lena Headey as Cersei Lannister in Game of Thrones

Game of Thrones
Arts and Entertainment
New book 'The Rabbit Who Wants To Fall Asleep' by Carl-Johan Forssen Ehrlin

books
Arts and Entertainment
Calvi is not afraid of exploring the deep stuff: loneliness, anxiety, identity, reinvention
music
Arts and Entertainment
Edinburgh solo performers Neil James and Jessica Sherr
comedy
Arts and Entertainment
If a deal to buy tBeats, founded by hip-hop star Dr Dre (pictured) and music producer Jimmy Iovine went through, it would be Apple’s biggest ever acquisition

album review
Arts and Entertainment
Paloma Faith is joining The Voice as a new coach

TV
Arts and Entertainment
Dowton Abbey has been pulling in 'telly tourists', who are visiting Highclere House in Berkshire

TV
Arts and Entertainment

TV
Arts and Entertainment
Patriot games: Vic Reeves featured in ‘Very British Problems’
TV review
Arts and Entertainment
film review
Arts and Entertainment
Summer nights: ‘Wet Hot American Summer: First Day of Camp’
TVBut what do we Brits really know about them?
Arts and Entertainment
Dr Michael Mosley is a game presenter

TV review
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
SPONSORED FEATURES

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    A groundbreaking study of 'Britain's Atlantis' long buried at the bottom of the North Sea could revolutionise how we see our prehistoric past

    Britain's Atlantis

    Scientific study beneath North Sea could revolutionise how we see the past
    The Queen has 'done and said nothing that anybody will remember,' says Starkey

    The Queen has 'done and said nothing that anybody will remember'

    David Starkey's assessment
    Oliver Sacks said his life has been 'an enormous privilege and adventure'

    'An enormous privilege and adventure'

    Oliver Sacks writing about his life
    'Gibraltar is British, and it is going to stay British forever'

    'Gibraltar is British, and it is going to stay British forever'

    The Rock's Chief Minister hits back at Spanish government's 'lies'
    Britain is still addicted to 'dirty coal'

    Britain still addicted to 'dirty' coal

    Biggest energy suppliers are more dependent on fossil fuel than a decade ago
    Orthorexia nervosa: How becoming obsessed with healthy eating can lead to malnutrition

    Orthorexia nervosa

    How becoming obsessed with healthy eating can lead to malnutrition
    Lady Chatterley is not obscene, says TV director

    Lady Chatterley’s Lover

    Director Jed Mercurio on why DH Lawrence's novel 'is not an obscene story'
    Farmers in tropical forests are training ants to kill off bigger pests

    Set a pest to catch a pest

    Farmers in tropical forests are training ants to kill off bigger pests
    Mexico: A culture that celebrates darkness as an essential part of life

    The dark side of Mexico

    A culture that celebrates darkness as an essential part of life
    Being sexually assaulted was not your fault, Chrissie Hynde. Don't tell other victims it was theirs

    Being sexually assaulted was not your fault, Chrissie Hynde

    Please don't tell other victims it was theirs
    A nap a day could save your life - and here's why

    A nap a day could save your life

    A midday nap is 'associated with reduced blood pressure'
    If men are so obsessed by sex, why do they clam up when confronted with the grisly realities?

    If men are so obsessed by sex...

    ...why do they clam up when confronted with the grisly realities?
    The comedy titans of Avalon on their attempt to save BBC3

    Jon Thoday and Richard Allen-Turner

    The comedy titans of Avalon on their attempt to save BBC3
    The bathing machine is back... but with a difference

    Rolling in the deep

    The bathing machine is back but with a difference
    Part-privatised tests, new age limits, driverless cars: Tories plot motoring revolution

    Conservatives plot a motoring revolution

    Draft report reveals biggest reform to regulations since driving test introduced in 1935