A sky worth waking up for
So how's winter going for you? Even if you enjoy this season, this is about the time that winter really begins to drag.
Would it help if I told you that winter is the shortest season of the year, at least astronomically?
It all has to do with the fact the Earth travels faster around the sun this time of the year. The Earth's 365.25 day orbit around the sun is not exactly circular but slightly elliptical.
This time of year the Earth is more than three million miles closer to the sun than it is in the summer, and because we're closer, the sun has a stronger gravitational tug on our world. That causes the Earth to move more rapidly around the sun this time of year.
The same thing happens when you tie a string around a doughnut and swing it horizontally above your head. If you shorten the length of the string and swing it with the same force it will move faster around your head. This time of year the “string” between the Earth and the sun is shorter so the Earth moves faster.
How much faster? Actually quite a bit.
This time of year Earth is chugging along on its orbital track at well faster than 67,500 mph, more than 2,000 mph faster than it does in the summer.
Because of that lazier summer pace, it takes 94 days to go from the first day of summer to the first day of autumn, but because the Earth pounds the orbital pavement at a faster pace in winter, it only takes 89 days to travel from the first day of winter to the first day of astronomical spring.
Feel better about winter now?
If that doesn't help, use a tool that astronomers have in their toolbox: time travel.
Classically, astronomers used the speed of light to travel back in time.
The speed of light is 186,300 miles per second, and a light year is the distance light travels in one year's time. That works out to be nearly six trillion miles. So if you see a star that's one hundred light years away, it works out to about six hundred trillion miles, but also by definition you're seeing that star not as it appears right now, but as it appeared a century ago. A hundred years in the lifetime of stars is just a speck in time.
Thanks to the Hubble Telescope and other advanced telescopes both on land and in space, astronomers now have the ability to see galaxies that are more than ten billion light years away. When you see galaxies that far away, you really get a look back into time as to what those galaxies looked like in the early stages of our known universe.
Everyday stargazers like you and me can also travel forward in time. Now we can't go forward billions of years, but we can advance our view into space a few months. We don't need the Hubble telescope.
What we do need is a good alarm clock to get us out of bed in the early morning hours. If you can get yourself out of the sack and under the stars about an hour before morning twilight you can see the same night sky that you will see in the early evening in late June. You can experience early summer in the middle of winter, at least astronomically. You can see summer stars without mosquitoes!
The particular set of constellations and their placement in the sky at any one time depends on what direction into space your part of the Earth is facing.
It just so happens that before morning twilight from our vantage in Butler we're facing the same direction in space that we do in the early evening in late June. In fact, if you want to get an advance viewing of your evening skies four to five months in the future, check out the sky just before morning twilight invades.
While you're out there with your morning cup of coffee this week checking out the summer skies, you can watch the waning moon passing by some bright stars and planets.
On Tuesday morning look for two stars hanging just above the last quarter moon that actually looks like a half moon.
The star just to the upper left of the moon is Spica, the brightest star in the constellation Virgo. The other “star” a little farther above and to the right of the moon is actually the planet Saturn.
Take a look at it with even a small telescope and you should see Saturn's ring system and some of its moons, although Saturn itself will be very tiny. This month it's pretty far from Earth at more than 850 million miles away. It will be lot closer this spring.
On Friday morning around 6 a.m. the moon will be a skinny crescent in the eastern sky, and there will be a decidedly reddish star just to its lower left.
That's Antares, the brightest star in the constellation Scorpius. Antares, a red giant star, is more than 600 light years away and is so large that if you put it in the place of the sun in our solar system, the planets Mercury, Venus, Earth and Mars would all reside inside Antares. You wouldn't experience winter weather anymore!
To the far left of the Moon and Antares in the southeast is the brightest starlike object in the sky this winter.
It's the planet Venus, just more than 75 million miles from Earth right now. With a small telescope you won't see any surface features on Venus since it has a thick poisonous cloud cover, but what you will see is that it looks like a half moon.
Just like our moon, Venus goes through phases and shape changes as it orbits the sun inside our Earth's solar circuit. Planets reflect sunlight like our moon does, and as the angle between our Earth, the sun and Venus changes, we see our next door neighbor in the solar system changing shapes.
If you're up early on Saturday and Sunday mornings you're in for a real treat as the crescent moon will be practically kissing Venus.
On Saturday morning look for Venus just to the left of the Moon and on Sunday morning a very thin crescent moon will hang just below brilliant Venus. That's definitely worth waking up for!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Pennsylvania Starwatch,” available at bookstores and also at his website www.lynchandthestars.com.
