Summertime and the Reading Is Easy : A Dangerous Darkness : Nothing is what it appears to be : TOTAL ECLIPSE. <i> By Liz Rigbey (Pocket Books; $22; 472 pp.)</i>

To look up into the sun is to know the familiar. We know its heat; we know its light. We understand that without it, there is darkness, and that with this darkness comes a certain fear. And when the moon passes between the sun and the Earth, creating what is known to be a solar eclipse, the blackness is deeper still, the potential for evil palpable. For a number of heart-stopping minutes, day is bizarrely transformed into night, making for an eerie canvas in which nothing is what it appears to be.

Which is precisely the point of Liz Rigbey’s powerfully suspenseful and psychologically intriguing first novel: In “Total Eclipse,” set in and around a Northern California observatory with the big telescope as metaphor, appearance and reality are light-years apart.

At the heart of Rigbey’s dark story is Lomax, a brilliant astronomer obsessively drawn to Julia Fox, a young beauty accused of killing her decades-older husband and his daughter, Gail. They are brutal murders, two people shot dead almost at point-blank, Gail’s face obliterated beyond recognition. There’s an eyewitness who definitively places Julia at the scene of the crime, but she vehemently denies it.

Julia couldn’t have done it, Lomax reasons. She worshiped her husband, didn’t she? Is it not true, too, that she adored her stepdaughter, nearly the same age as she, an intelligent but dumpy woman devoted to her father? From everything Julia has told Lomax, he believes the three were storybook happy. He is, after all, a scientist, with what he calls an astronomer’s instinct, and he should be able to track down the real killer. “I spend my whole time trying to see past the bright lights of our galaxy into deep space, which is often more revealing,” he tells Julia’s lawyer in explaining why he should be brought into the investigation.

As Lomax looks into the darkness in his attempt to unravel the mystery surrounding the murders, what begins to be revealed are some startlingly unseemly facts. The 58-year-old Lewis Fox, Julia’s dead husband, had a penchant for very young girls, one of whom might possibly have been his own daughter. Vicky, Fox’s first wife and a hopeless alcoholic, pathetically babbles on like the village idiot, but her version of the truth may not be as distorted as it at first seems. Julia, in retaliation for her husband’s many infidelities, sleeps with her stepson. And Gail, far from being Julia’s good friend, is nearly psychotic in her desire to be noticed by dear old Dad.

Along the way, we--through Lomax’s eyes--are introduced to a uniquely entertaining collection of people: a psychiatrist who consistently refers to himself in the third person while munching on twigs and branches and blossoms. A woman known as “the Nose” who can tell you the name of the soap you use and can smell cancer and fear. A loopy, chain-smoking librarian named Mrs. Cleaver who’s an armchair sleuth. A grandstanding D.A. straight out of central casting. And a fabulously lovable dog named Deputy.

Rigbey, who lives in England but spent much of her early life in Colorado and California, has managed to create a real sense of foreboding through some intricate plotting. In placing her characters in the oddly exotic world of astronomy, she draws on and successfully employs a host of images serving to underline her premise that within us all, a dangerous darkness can often obscure the light.

There is, for instance, this description of Lomax’s reaction to the eclipse itself: “As the sky darkened, the earth became still. A big black disk was gliding slowly across the sun. Lomax knew it was the moon, he had just explained it was the moon, but it was not the familiar pale moon. This was a dark, menacing sphere and, like a big fish, it was gradually swallowing the sun. . . . It was not really night. It was day. It was day without light and without hope.”

There is, too, the handmade telescope that Lomax’s mentor, Dr. Berlins, fashions and presents to him as a gift: “Lomax did not know exactly what error Berlins had made in his mirror grinding. . . . But some distortion of the light made everything, even subjects as familiar as his own children look unrecognizable.” You might learn something from it, the good doctor tells Lomax. What he learns turns out to be who killed Lewis and Gail Fox, and why.

Distortions and refractions. The familiar and the unknown. That which is recognizable and that which is grotesque. These are the potent themes traveling through Liz Rigbey’s big sky, a vast universe in which good is sometimes eclipsed by evil.

“Total Eclipse” is also available (abridged) read by Michael O’Keefe on four audiocassettes from Simon & Schuster ($22).