If you’re not one of the 17 million readers of astrologyzone.com or one of the users of the app of the same name, you may not have heard of Susan Miller – yet. But for any astrology-obsessed millennial, she is the queen of fortune telling, single-handedly responsible for fuelling their obsession with all things celestial. Somehow she has managed to turn the mystical, ancient pseudo-science of astrology into a world-wide phenomenon – her website enjoyed more than 310m page views in 2018 and this year traffic looks set to double.

Miller’s readers come from every country in the world, she’s written 11 bestselling books, and currently writes for magazines in eight countries. She also has a monthly TV show and regularly gives personal readings. She has a devoted celebrity following, including Cameron Diaz, who allegedly consulted her for advice before buying a house, Justin Theroux, Pharrell Williams and Alexa Chung.

Miller clearly enjoys the reach and power of her online predictions. “It makes me feel accomplished and I am grateful that people hand their hearts to me,” she says. But ask Miller the real reason she believes she appeals to a younger generation and she insists it’s not completely down to her. “The internet. That’s what has made astrology so popular,” she says. “In the old days you had to go to the library or buy a magazine.”

Back then, astrology had a more traditional, fusty image and was viewed more sceptically. Now perhaps it’s the need to find direction and spiritual meaning that has made a younger generation less cynical. So there are social networking apps, like Co-Star, which not only offer daily advice based on your birth chart, but also tell you how compatible your friendships are.

Millennials are looking for answers from a higher authority

Astrology predictions are perfect for posting online, particularly if you are willing to connect with your readers in a way that astrologists in the past never would. “I love Twitter and Instagram,” enthuses Miller. “It’s there that I can really respond to people. They say people lie on the internet, but not to me.”

Miller is shrewd about exactly how she engages with her readers, never keen to give too much away. She refuses to reveal her age (she was born in the late 50s), because she wants everyone that reads her to feel she could be the same age as them. Cleverly, she decided early on that rather than dumb down, she needed to distance herself from cartoon-esque astrologers like Mystic Meg.

So when Miller started her horoscope pages for Time Warner in the mid-90s, she decided to write at least 1,000 words on each sign – she knew a detailed reading would mean people would want to return to the site every month. On her website, she offers a 12,000-word horoscope each month, but there’s also the app with shorter highlights, a daily celestial titbit. Her website is free to browse, but for a longer reading you need to subscribe – £44.99 a year or £4.49 a month. “I write a horoscope and a roundup for each sign, every month. It comes to about 12,000 words, more if there is an eclipse.”

From the off she wanted to write for men and women, rather than focus on a traditionally female market. Miller’s appeal is global yet her largest fanbase is in the UK – perhaps as a nation we are more attuned to our cosmic selves. On her website, the reading for my sign (Gemini) tells me that this month I will have a good day for love, a call about TV, but I will need to follow my intuition about work. I should also take my inspirations seriously because the universe is listening. The whole reading runs to seven pages. It is easy to understand why millennials – a stressed-out generation who have been told that everything has been ruined, from the housing industry to handshakes – are looking for answers from a higher authority on love, relationships and jobs, while still feeling unique. Handy then, that no two birth charts are the same.

While she may have nailed the astrology market, her working life is still modest. Like many freelancers she works from home (even if home happens to be the Upper East Side in Manhattan), from the comfort of her sofa with the TV quietly burbling away in the background. “I have the rolling news on. Sometimes I’ll hear a great word and try and use it later,” she laughs.

Miller is actually a second-generation astrologer – her mother studied the craft back in the 1940s. At the time, it wasn’t part of popular culture, so she only did readings for friends and family. And, of course, her daughter, who was born with a birth defect. Other than predicting the internet, and her daughter’s future career, she also predicted that Miller’s leg, which had paper thin arteries that led to internal bleeding throughout her childhood, would heal by the time she was 14.

If I have bad news in the stars, I look for good parts in the chart

“I would have these terrible attacks, that would lead to me being bed bound for about eight weeks each time. Eventually, when I was 13 and 11 months, it was discovered I had been bleeding internally and I was hospitalised for 11 months; the tourniquet they put on was so tight it left the leg deformed.” It is destiny not fate that this event led her to learn astrology. “I asked my mother to do my chart to see if I would walk again, but she wouldn’t, so I wrote to Horoscopes Magazine,” she says. “They printed my letter and said that I had good aspects for health, but I didn’t understand all the terms they were using, so I asked my mother to help me understand them.”

Learning astrology is complex – you have to think in calculus – and Miller, who was home-schooled, with a maths tutor, studied with her mother for 12 years. Now she is accredited by the International Society for Astrological Research. After graduating from NYU with an MA in business, she worked as a commercial photography agent, but gave readings to those around her as a means of thanks.

“There was one client who introduced me to his wife, she was the creative director of Warner books. We became friends and one day I said to her she should buy a lottery ticket. I said: ‘You will win in the last two weeks of December.’ She bought a raffle ticket from a friend’s son. And on New Year’s Eve, her phone rang; she had won a Porsche.” Four years later, the same women helped Miller negotiate her first book deal.

Such is the cult and power of Astrology Zone that the New York Times once wrote a piece about her being two hours late with the content. It is obvious she really cares about her readers, replying to them on social media, and spending an hour or so each day going through emails with her assistant. “Although, I prefer the phone.”

Each star sign takes about seven hours to write and she works a few months in advance. She writes a round-up for each and a reading. Once written, they are sent to an editor and factchecker. “You feel a great responsibility to people and you can feel the tension – you have to be accurate with what you say. I don’t have trouble deciphering the stars, but if I have difficult news, I look for the good parts of the chart and try and help emphasise them, and show the reader how to negotiate the difficult parts.”

We are the first few generations in human history to see detailed images of what stars look like. The ancient Babylonians, who charted lunar cycles on the walls of caves 25,000 years ago, would have only seen them twinkling in the skies. Even then, they understood that constellations would appear during different times of the year and that the moon had an influence on bodies of water.

There are, of course, sceptics. “People find it irresistible to make fun of things they don’t understand,” Miller says. “I would just like a scientist to study astrology or to have their chart read, or at least read one of my summaries.”

In between all of her work, she also enjoys doing readings for her family. “Everyone was asking when my daughter would get married, but she couldn’t decide on a day. I said: ‘Uh-oh I need to get involved here,’ so I picked the day… If there’s a bad aspect involving the planets you have to wait for them to move. I made them wait for two years.” Was it worth postponing? Of course. “They had a beautiful wedding and it all worked out.”

Susan Miller will host a residency at Daios Cove, Crete, 2-9 June. For information, go to daioscovecrete.com