'Dog Days of Summer': What are they, and what do they mean?

PHILADELPHIA - What pops in your head when you hear "Dog Days of Summer"?  Warm, humid weather? However, the origin of the saying actually relates to space.

The brightest star in our night sky is Sirius, which is nicknamed the dog star. That nickname comes from its constellation; it's part of a group of stars called The Great Dog.

But, don't go out looking for Sirius tonight! The best time to see Sirius in the night sky is the middle of winter.  

In the middle of summer, it's hidden in the sky because it's out during the day.

These days, Sirius and our sun rise around the same time - about 6 a.m. Because the Sirius star is in sync with our star, it got linked to all the hot weather our star brings us this time of year.

The tilt of the Earth leads to sunlight being more focused on our part of the Earth these days.The more focused the sun is on an area, the warmer it gets.

July is the hottest part of the year. Average highs peaks at 88, and that's the case most of July.  

Because average is 88, it's also typical to have highs in the 90s. It turns out it's typical to have a month's worth of 90-degree days each year. We average 30 days in the 90s. So far this year, we've had 25 days in the 90s.

The warmer the air gets, the more humid the air gets. So, the hottest time of the year often has a lot of humid days.

While you could say the weather has gone to the dogs when hot and humid, really, it's just gone to one dog - the dog star.

By the way, Sirius gets a different nickname in the winter months. It's called the rainbow star. That's because it flickers and looks multicolored when it's low in the sky.  

A Lehigh Valley NASA Ambassador shared a video of how that looks through his telescope.

If you want to stargaze tonight, check the Weather Authority forecast.