Looking Up column: See where we are headed in the night sky
Where are we headed? There are a lot of ways to look at that. How about the constellation Hercules?
We’re on the ride of our lifetimes, whether you fully know it or not. All 7.8 billion people are passengers on this planet we call Earth, which is not only circling the sun but is on an interstellar voyage through the Milky Way.
The sun takes its entire family with it on this trek. Sorry, there’s no rest stop on the way, but the view is fantastic all the way.
Hercules the Strong Man is right overhead as darkness falls in mid-July, as seen from mid-northern latitudes.
Just look straight up. When you do, you are “keeping your eyes on the road” as we hurtle onward.
Astronomers call the sun’s direction as the “solar apex”.
The exact spot is southwest of the brilliant star Vega, which you will see on a star map is in the neighboring constellation Lyra the Harp. When the mid-summer sky gets dark, you will see Vega shining high up in the east.
The sun, along with several hundred billions of other stars making up the Milky Way galaxy, is orbiting the galactic center. Our spiral galaxy has an estimated diameter of 100,000 light-years - it takes that many years for light to pass from one side to the other.
There are several estimates of the time it takes for the sun to make this trip; a typical estimate is 230 million years, moving at about 140 miles per second.
That’s really fast by earthly standards. The sun, however, is 865,370 miles wide. At that speed, it takes the sun 257.5 hours (about 10.7 days) to move its own width! It’s a LONG way around the galaxy.
If you live for 100 years, you will have traveled 122,640,000 miles.
To see approximately the direction, using a star chart, find the star Omicron Herculis in Hercules and the star Beta Lyrae in Lyra, connecting a line between them, the solar apex is about halfway.
Astronomers keep track of positions on the sky with map lines similar to latitude and longitude on a world map or globe. On the sky - the celestial sphere - they are called declination and right ascension (R.A.).
The solar apex is at +30 degrees declination and 18 hours, 28 minutes R.A.
Don’t get car sick, but you can also look back and see from where the sun came. The “solar antapex” is on the direct opposite side of the celestial sphere, located on the constellation Canis Major the Big Dog, just east of the star Furad. Canis Major is to the lower left of Orion and is in the winter evening sky (for northern hemisphere folk).
While looking up on a July evening at Hercules, note the “Keystone,” four stars making an uneven square. Using binoculars, look between the Keystone’s stars on the right (west) side, for what appears as a very fuzzy star. This is the grand globular cluster M13, hundreds of thousands of stars packed near each other in a sort of celestial ball. It’s an amazing sight in a telescope of 6-inch or larger aperture.
Be sure to see the bright planet Jupiter low in the southeast, between 10 and 11 p.m. To the lower left is the planet Saturn, not quite as bright.
Last quarter moon is on July 12.
Keep looking up at the sky!
Peter Becker is managing editor at The News Eagle in Hawley, Pennsylvania. Notes are welcome at firstname.lastname@example.org. Please mention in what newspaper or website you read this column.