First I want to tackle the question, "What is beauty?" Or perhaps more fittingly, "What makes something beautiful?" I'll think about the other question regarding "being in the moment" at a later time.
It seems there is more than one type of beauty, two that I perceive in the world, although I'm sure they both spring from the same source (whatever that ultimate source may be).
1. Beauty that inspires awe in a human being. That is to say, the beauty people see in nature, or in anything that exists on a grand scale. This type of beauty is interesting because, unlike other forms of beauty, everyone usually agrees that what they are perceiving is beautiful (maybe there are examples that refute this claim, but for the sake of argument, I'm going to stick with this idea).
The vast expanse of the Grand Canyon, an ocean, a clear blue sky, mountains, etc. are all described as beautiful. But why? When I think of how the word "beauty" is used in day-to-day vernacular, its use doesn't quite fit with the beauty found and appreciated in nature.
This is because "awe-inspiring" beauty is just that: awe-inspiring. The size and grandeur is almost overwhelming to the senses. Nature is literally bigger than us, and perhaps part of what we perceive as beautiful is the reminder of how small we are (in a sense) and that we are truly part of something much bigger than the individual.
Natural beauty doesn't have to be on a large scale though. It's true we also see beauty in detail. For example, the more you pay attention to the life that surrounds you in a forest, the more you see and the more you appreciate. What was just a tree, upon closer examination, is actually an intricately woven piece of bark with thousands of leaves, all varying slightly in color - the leaves have designs on them and stems, there are insects crawling around, bacteria growing, atoms, electrons, neutrons, protons etc! Of course, you don't see the latter, but I think our minds find the details in nature just as tantalizing as the big picture. Maybe seeing nature as beautiful is an appreciation of creation itself.
Beauty is also a term ascribed to that which has been created by humanity. Spiritually, many people already believe we are all reflections of God, so to see beauty in what we create here on earth would merely be an extension of the appreciation for God's creations in nature. Skyscrapers, for example, inspire an awe in me that is akin to the feelings I experience when contemplating a mountain range or a lush forest.
What do people create that is considered beautiful? Music, art, dance, literature - all the biggies.
All these things are beautiful because they reflect the perfection of existence. That is not to say, everything is perfect, but the fact that everything exists, is alive and breathes, makes it so.
2. Imperfection is beauty. This is, now that I think of it, related to the above statement about beauty, but I think it deserves its own explanation.
Have you ever noticed that when something is too "perfect" it doesn't come across as very beautiful? When people on television whiten their teeth to the extreme, it often looks odd, and not very attractive. Their teeth are
too white. In fact, someone with a more natural-looking smile comes across as more beautiful.
A wooden floor that is super glossy and perfectly installed doesn't strike me as beautiful - on the contrary, a more rustic wooden floor without so much finish seems a millions times more beautiful (maybe this is just my preference though

)
The world has dirt, mud, kinks, and bumps - it is hardly smooth, but that doesn't make it less beautiful. That's what
makes it so beautiful.
Imperfection also provides the opportunity for contrast and comparison. Oftentimes we only appreciate the good things in our life because of the bad things. They balance each other out and that's what makes life beautiful.
Sunny days and warm weather are more meaningful after the rain, and after the cold snowy days of winter.
As someone mentioned in another post, it is often the unexpected diversion from the norm or from the "smooth road of perfection" that makes something wonderfully beautiful, and literally, Divine. When something hits you right in the heart as fundamentally beautiful, you feel a primordial connection to a truth we all share. Maybe it is this brief understanding of a deeper, shared truth that we perceive as "beauty."
Would we even have amazing poetry or music or literature if the artist had not undergone some sort of dark emotion or ventured through the grimy side of life? Probably not. Good art - beautiful art - taps into the Truth.
It is a creation of the human soul, a reflection of life - and life is beautiful in all its misery, joy, hardship, and bliss.