This expression has been in figurative use since the late 16th century. Literally, in technical astrological use, an ascendant is the sign of the zodiac that is just rising above the : eastern horizon at a particular moment.
dust and ashes
Used to convey a feeling of great disappointment or disillusion about something. Often found in the fuller form turn to dust and ashes in your mouth, the phrase is used in the Bible as a metaphor for worthlessness for example in Genesis 18 : 27 and the Book of Job 30 : 19. It derives from the legend of the Sodom apple or Dead Sea fruit whose attractive appearance tempted people, but which tasted only of dust and ashes when eaten.
rake over the ashes = rake over old coals
revive the memory of a past event which is best forgotten - chiefly British
rise from the ashes
Be renewed after destruction
In classical mythology, the phoenix was a unique bird resembling an eagle that lived for five or six centuries in the Arabian desert. After this time it burned itself on a funeral pyre ignited by the sun and fanned by its own wings and was then born again from the ashes with renewed youth to live through another cycle of life. The simile like a phoenix from the ashes is used of someone or something that has made a fresh start after apparently experiencing total destruction.
turn to ashes in your mouth
become bitterly disappointing or worthless
This phrase alludes to the Dead Sea fruit - a legendary fruit which looked appetizing but turned to smoke and ashes when someone tried to eat it. The fruit are described in the Travels attributed to the 14th-century writer John de Mandeville.
1995 - Guardian - Those who marvelled at the phenomenal climbing feats of Pedro Delgado in the 1988 Tour found words such as heroic and Herculean turn to ashes in their mouths during the probenecid (a masking agent) scandal.
ask for the moon = cry for the moon
ask for what is unattainable or impossible – British
The moon in this expression, which dates from the mid 16th century, stands for something distant and unattainable, as it does in promise someone the moon.
ask me another
used to say emphatically that you do not know the answer to a question – informal
ask no odds
ask no favours – US
a big ask
a difficult demand to fulfil – informal
don't ask me
used to indicate that you do not know the answer to a question and that you are surprised or irritated to be questioned – informal
I ask you!
an exclamation of shock or disapproval intended to elicit agreement from your listener – informal