Re: why does the sun rise earlier in sydney then it does in melbourne

The sun's motion over the course of the day is due to the Earth's rotation.
 As the earth rotates, the sun appears to rise in the East and set in the
West.  Since Sydney (longitude 151 12 31 E) is further east than Melbourne
(longitude 144 57 47 E), the sun will rise over Sydney's horizon first.

The sun (and all celestial bodies) travels 15 degrees/hour across the sky.
 So, since the difference in longitude is about 6.25 degrees, the sun
should rise about 25 minutes later in Melbourne than Sydney.

In some cases, the latitude difference can matter.  An extreme example of
this would be someone on the equator vs. someone within the antarctic
circle during southern hemisphere summer; the person on the equator will
see the sun rise and set, while the person in the antarctic circle will
never see the sun set.  However, the latitude difference between Sydney and
Melbourne has very little effect since the difference is so small.