Orbs Above the Great Spire

In the photo below  (taken on May 8, 2015), we see an orb with a deep blue color above the Bank of America tower in New York City.

The photo below (taken on May 1, 2015) shows a purple-colored orb above the same huge spire.

Here is another photo from the same day, showing an orb (with a different color) near the same spire:

There was no fog, mist, rain, or other precipitation on these nights.  None of the orbs shown is the moon.  The last two photos were taken on a night when the air quality (as posted on airnow.gov) was listed as "good," with a rating of 28 (anything below 50 is considered good).