A red 'sun' that pulsed back and forth in an unbelievable way.

Me and my sister (who were about 9 and 8 years old) were in our back garden playing and we spotted in the sky what we thought was the sun. It perplexed us that the 'sun' was much more red than usual and was not that low on the horizon. After looking at it over the fence for about 30 seconds the object started to pulsate back and forth (it is very hard to explain how it did it). It was as if it was pulsing bigger and smaller towards us and then away from us. We both ran away into the house and I remember before I ran indoors I got on another fence to check if what I was seeing was real. I started to cry when I saw it from this view and ran indoors. We told our parents to come out to see it and after about 2 minutes after we had convinced them to come to have a look the red light in the sky had gone and was nowhere to be seen. The object was a dark but vibrant red and was circular. The pulsing it did was eerie and it scared us both in the way it pulsed, it was just unlike anything I had ever seen before.
Witness indicates date of June 31.  June has only 30 days.  We have amended the date above.  Date is approximate.  PD