When the scalpel-sharp Peter Robinson of Popjustice.com recently interviewed the elder Ms Minogue of Melbourne, he told her what he thought a "Kylie moment" was. He said, "[It's] a bit in a song that inspires a slightly unexpected surging emotion, happiness but also some sadness, with a sense of being slightly close to tears for no real reason", and Kylie agreed, mentioning a musical moment in her new video, and a "sound [that] made me make lots of firework noises". While this is an impressive skill in its own right - especially if the diminutive Australian can master the pop of a Catherine Wheel - you sense she was avoiding the nub of what Robinson was really saying. Which is that melancholy, and vast oceans of it, have always been part of Kylie's charm, ever since she first appeared in a car on Sydney Harbour Bridge, the wind in her hair, thinking that she should be so lucky.

Kylie's best moments have always been dunked in a mood of euphoria both poignant and pure, every gleaming chord progression glistening with tiny diamond tears. The context helps, of course, especially if you have grown up with the golden-haired girl-next-door since 1987, and watched the tomboy mechanic soap star get away with sloping off with Michael Hutchence, having her head bashed in with a rock by Nick Cave, and parading around in various shades of tiny hotpant. The wider world forgives Kylie everything - even her sexiest moments, of which there have been many - thanks to a fresh-faced figure in our collective consciousness who isn't really her, who is above reproach. Whatever she does, Kylie is endlessly lovable, somehow beyond criticism.

But while Kylie's nearest touchstone in terms of her image is probably Olivia Newton John, and in terms of her songs, the bright-eyed, heart-wrenching pop of ABBA, her best songs (OK, let's go…'Can't Get You Out Of My Head', 'Confide In Me', 'Better The Devil You Know', 'Slow', 'Hand On Your Heart', 'Put Yourself In My Place', 'Wouldn't Change A Thing', 'The One' from her last album, X) - are touched with a different, more interesting kind of danger, full of doubts about the future, glossy with fear and desperation, that all these dreams of love and fulfilment might not happen after all. Thinking about this, her contemporary context looms suddenly. Her cancer in 2005, although now long in remission, and her advancing years in pop terms - although at 42, she shows no signs of stopping, and why the hell should she - could add different shades of emotion to her brilliant pop songs, something that Robinson also recognises in his interview.

This is the challenge, but for now, Kylie almost totally sidesteps it. And despite album artwork that suggests a more mature, defiant woman, Aphrodite is business as usual in terms of its style - all glittery disco-pop, pounding and beating, this time with the genre's top producer, Stuart Price, at the controls. This has become Kylie's default setting after her dabbles with indie and harder electronic sounds, but although it is often harmlessly lovely to the ear, its can get a little samey. The album's get-to-it lyrics can also get mind-numbingly monotonous, often coming across as the work of a over-enthusiastic self-help advocate. "Dance! It's all I want to do, so won't you dance" demands the opening track, 'All My Lovers'. "Put your hands up, if you feel love tonight," insists 'Put Your Hands Up'. 'Get Outta My Way' castigates us, whoever we are, for being "so boring" for not wanting to "take a chance" - although there is a certain joy to be had in hearing Kylie whine the word "boring" - while 'Better Than Today' raises the odds even higher, wondering out loud, as it shimmies like a Scissor Sisters b-side, "what's the point in living if you don't want to dance?" These are nothing more than simple pop sentiments, certainly, but here they feel a little empty, and colourless; the words of a woman protesting too much.

It doesn't help that many of these are fun, but not fabulous, songs, templates for brilliant club remixes rather than great things in their own right. Tiny elements shine out instead. 'All The Lovers'' primitive Yazoo-flavoured synthesiser riff certainly bewitches, while 'Cupid Boy' is full of delicious details - a guitar introduction that could be straight off the Lonelady album, eerie vocoder vocals announcing its chorus, and the woozy power hearing Kylie repeat the phrase "start hitting me up". 'Closer' is also a particular thrill, blinking in the sunlight of late 70s cosmic pop and prog, with a creeping, claustrophobic bassline leading us to its centre. It's like Kylie taking on Muse - no! wait! come back! - but somehow this weird alchemy works.

But the most immediate track, by several million light years, is a song Peter Robinson rightly says should have been Kylie's comeback single after her illness. This is the title track, 'Aphrodite'. As Kylie sings, "this song lets you in", she gives us a tiny glimpse into the soul of the girl behind the shimmer. A piece of unapologetically bold and brazen pop buried in the album's middle - there has been no news of it being released a single - it contains a line that hits like a hammer to the heart. As Kylie sings, "It's the truth, it's a fact/I was gone and now I'm back", you wish she would go further, offer more of herself.

These words also take us back to Robinson's interview, where he drew Kylie into saying, yes, she should write about those darker moments in her life, and, yes, she would love to do a two-week anti-tour in a club in Soho, packing her set full of songs the fans hold especially dear. These words also took me back to the glorious pop moments of hers that have marked my little life, the most recent being when she sang 'I Should Be So Lucky' as a torchsong on Jools Holland's Hootenanny in 2007. This reminded me of the depths that have always been there in some of Kylie's shiniest songs, and as I put 'Aphrodite' back on, it also reminds me of what I still want, as I wait for the goddess to reveal herself utterly.