This is as good a point as any to address this issue. What is meant by “day” in Genesis? And: What does “day” mean in this creation passage?
People get all worked up over these questions and they do so for all the wrong reasons. Since this passage is composed with some very specific theological teaching in mind, none of which are scientific in nature, the questions about days in Genesis 1 and 2 are little better than distractions.
To the first question. Many will argue till they are blue in the face that the term “Yom” can only mean a 24 hour day. That is silly, since in this very verse, day has two senses. First, God calls the light portion of the 24 hour period “day” and the other, dark portion “night.” So we already have a meaning other than 24 hours. Then, in the second creation passage, beginning in 2:4, we get the reference to “the day that the Lord created the earth and the heavens.” That can’t be a 24 hour period, because it would contradict chapter one. But, have no fear, here in chapter 1 the term day is referring to a normal day, and we are presented with an account of creation that happens in a week-like-pattern. So, what is meant by “day” in this hymn of creation is the regular day, even before there was a sun or a moon to measure such a thing.
But when you ask what this week, these seven days of creation, means in this passage, you don’t have such a clear-cut answer. Yes, if God so desired He could have created everything in the universe in 8,640 minutes (with another 1,440 of rest). But if you insist that that is the intended teaching in this passage you might be mistaken. It is certainly not a good idea to require people to believe that as a prerequisite for orthodoxy.
Some people look at the apparent and clear evidences of an old universe and say that God created everything with an appearance of age. In other words, a misdirection that renders everything we see as untrustworthy. That is something that has a lot of implications and we ought to be careful before we jump to that conclusion. While it is true that our reason is flawed and limited, and we can’t hope to explain everything in the universe, it is still an orderly universe operating in a structured and predictable way since it was created by a logical mind that belongs to a trustworthy Creator.
Others see the sense of structure being communicated in this passage and extrapolate that the days here symbolize longer, equal periods of time. That too is flawed, because if each day represents an era of creative activity then we could extrapolate that we are now in the seventh such period and God has ceased to be active in creation. The rest of scripture negates that idea.
The truer reading of this passage is to see an orderly, structured, creative, and organizing activity of a sovereign, almighty Creator. It is the revelation of that truth with little to no concern about the intricacies of how it was done, other than the Creator simply willed it to happen, that is being shown. That does not mean that any and all scientific theories can be shoehorned into this worldview, but there is a lot of room for speculation. Not that any of that is a truly worthwhile endeavor. (More on that to come.) God did it. He has told us all we need to know about how He did it.
However, if you are letting the “day” issue get in the way of sharing the story of Jesus, or if you are forcing people into one narrow interpretation before they can repent and follow; you are in the wrong.