Has the Catholic church ever voiced its view on the possibility of aliens' existence? Has the Catholic church ever acknowledged such a possibility as not contradicting the Bible? Or has it once said that the whole idea of aliens is absolutely non-Biblical as the humans are the center of God's creation or something like that?

So, once again: Has the Catholic church ever voiced its view on the possibility of aliens' existence?
The Roman Catholic Church has made no claims about the existence—or lack thereof—of extraterrestrial lifeforms, preferring instead to let astrobiologists and other members of the scientific community make that determination.
However, a number of Vatican astronomers over the years have theorized about the existence of such beings. Most notable among them is Father Jose Funes, director of the Vatican Observatory, who spoke to the L'Osservatore Romano (the Vatican newspaper of record) in 2008:

Father Funes said it was difficult to exclude the possibility that other intelligent life exists in the universe, and he noted that one field of astronomy is now actively seeking &quot;biomarkers&quot; in spectrum analysis of other stars and planets.

He even speculated that extraterrestrials might not bear the mark of original sin:

Asked about implications that the discovery of alien life might pose for Christian redemption, Father Funes cited the Gospel parable of the shepherd who left his flock of 99 sheep in order to search for the one that was lost.
&quot;We who belong to the human race could really be that lost sheep, the sinners who need a pastor,&quot; he said.
&quot;God became man in Jesus in order to save us. So if there are also other intelligent beings, it's not a given that they need redemption. They might have remained in full friendship with their creator,&quot; he said.

In 2009, when the Church hosted a conference to discuss astrobiology, Funes spoke out again:

&quot;The questions of life's origins and of whether life exists elsewhere in the universe are very suitable and deserve serious consideration,&quot; said the Rev. Jose Gabriel Funes, an astronomer and director of the Vatican Observatory.

Another Vatican scientist at the same conference, Brother Guy Consolmagno, speculated even further:

He said he was &quot;comfortable&quot; with the idea of alien life and asked if he would baptise an alien, he replied, &quot;Only if they asked.&quot;
&quot;I'd be delighted if we found life elsewhere and delighted if we found intelligent life elsewhere,&quot; he said.
&quot;But the odds of us finding it, of it being intelligent and us being able to communicate with it - when you add them up it's probably not a practical question.
&quot;God is bigger than just humanity. God is also the god of angels.&quot;
He said the characteristics synonymous with having a soul - intelligence, free will, freedom to love and freedom to make decisions - may not be unique to humans.
&quot;Any entity – no matter how many tentacles it has – has a soul,&quot; he said.
However machines were unlikely to be smart or human enough to have souls.

As they are under the employ of the Church, it's likely what they have said is at least nihil obstat, but definitely not dogmata.