Suffering through the dark days of winter? Would it help to know that winter is the shortest season of the year, at least astronomically?
That’s because the Earth travels faster around the sun this time of the year. The Earth’s orbit is slightly elliptical or ovalish.
This time of year the Earth is more than 3 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.
This time of year Earth is chugging along on its orbital track at well over 67,500 miles per hour, more than 2,000 mph faster than it does in the summer.
In summer the Earth takes 94 days to go from the first day of summer to the first day of autumn, but in winter it only takes 89 days to travel from the first day of winter to the first day of astronomical spring.
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, nearly 6 trillion miles. So a star that’s 100 light-years away is about 600 trillion miles away. You’re seeing that star as it appeared a century ago.
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 10 billion light-years away, a real look back in time as to what those galaxies looked like in the early stages of our known universe.
Everyday stargazers can also travel forward in time. Not billions of years, but we can advance our view into space by a few months. About an hour before morning twilight right now you can see the same night sky that you will see in the early evening in late June.
The particular set of constellations and their placement in the sky at any one time depends on what direction in space your part of the Earth is facing. Before morning twilight right now, Western Washington is facing the same direction in space as in the early evening in late June.
Also this week 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. Even with a small telescope you should see Saturn’s ring system and some of its moons although Saturn itself will be very tiny.
About 6 a.m. Friday the moon will be a skinny crescent in the eastern sky, The reddish star just to its lower left is Antares, the brightest star in the constellation Scorpius.
To the far left of the moon and Antares in the southeast is the brightest starlike object in the sky this winter: Venus, 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. Venus goes through phases and shape changes as it orbits the sun inside Earth’s solar circuit.
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.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Washington Starwatch,” available at bookstores. Check his website, www.lynchandthestars.com.
The Everett Astronomical Society: www.everettastro.org/.
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