The phrase "astonishing appearance" is correct and usable in written English.
It can be used to describe something or someone that has a surprising or impressive look or presence.
Example: "The magician's astonishing appearance on stage left the audience in awe."
Alternatives: "stunning look" or "remarkable presence."
After their astonishing appearance I approached them to express my admiration and gratitude.
Disabled, unconventionally beautiful (in the end, what other kind of beauty is there?), hectoring, free-spirited, politically confused, in her last years drawn to all sorts of spiritual and psychological claptrap - her complications add to the force of personality and the astonishing appearance that her paintings depict.
What was truly astonishing was the appearance of the New Jersey Catholic Conference in the case.
Moon's drumming, by contrast, is about putting things in the wrong place: the appearance of astonishing disorder.
An astonishing £11.8 million greeted the appearance of Cézanne's still life painted around 1893-1894 in oil on paper laid down on panel.
Doc gave up four hits, was helped by some erratic Royals base running and still has a 3-0 record with a 1.86 earned run average in five appearances in his astonishing return from the edge.
But possibly the most memorable link between tide and living creature is a very small marine worm, flat of body and with no distinction of appearance yet with one astonishing quality.
(Stevens is played by Ian Holm, in a performance that's all the more astonishing when put next to his appearance in one of the biggest movies of 1997: The Fifth Element).
The first appearance of pages from this astonishing new novel occurred in 1918, in The Little Review, whose foreign editor was Ezra Pound.
Given the rise of Russian Orc-ists, it's astonishing that the Eye of Sauron's appearance in the Moscow skyline is not their work.
And the astonishing Estelle Parsons swaggers commandingly in an 11 o'clock appearance as Jimmy's imperious mother.
