Jared May: What's Up August 5-13, 2021
What’s Up This Second Week of August
This upcoming week will likely hold several clear nights. This will be particularly rewarding given some of this week’s astronomical events, however, there will still be lots of haze in the atmosphere from the wildfires. Nighttime temperatures will be in the upper sixties and lower seventies. The conditions are almost always right on warm clear nights for dew to form, and may start condensing soon after sunset, which occurs around 8:40 PM.
This week be on the lookout for the new moon, a meetup of the moon and Venus, a rising Andromeda Galaxy, and some meteors as we approach the peak of the most famous meteor shower. I will also include a short section on black-hole hunting.
Sunday, August 8th will mark the official new moon. This is great news for stargazers and amateur astronomers alike since the moon glow in the night sky won’t wash out any deep-sky objects or stars. To give you an idea of how bright the full moon can be, imagine a star like Vega (one of the first stars to shine after sunset and one of the brightest) then multiply that brightness by 25,000 – that’s how bright the full moon is. The bright full moon can appear 40,000,000 brighter than the faintest stars the unaided eye can see.
On Tuesday, August 10th the newly formed waxing crescent moon will meet up with the third brightest object in the sky (behind the sun and moon), Venus. A more powerful telescope (focal length of 600mm or more) and an eyepiece (9mm or so) can resolve not just the craters and shadows that stretch across the lunar surface, but the phase of Venus. Careful observation will reveal that the inner planet is in its “waxing gibbous” phase.
On the evening of August 12, the crescent moon will be alongside Venus.
If you are more a fan of the winter skies than the summer skies, start looking low in the NE skies after sunset. You will see Cassiopeia, a famous constellation that looks like a big “W”. If you are familiar with the skies, you know that the Andromeda Galaxy hugs close to Cassiopeia. This galactic neighbor makes a fantastic beginner and expert astrophotography target. It also looks somewhat impressive through binoculars or a wide-field telescope.
If you like to stay up late (or get up really early, you can spot the “Fall” region which contains Cassiopeia and the Andromeda galaxy.
Coming up next week (Thursday, August 12th early morning) is the peak of the famous Perseids meteor shower. This shower runs from July 25 to August 18, so be on the lookout all this week, next week, and even the week after for fireballs. These meteors come from debris left behind from comet Swift-Tuttle. 1992 was the last time this comet was easily visible from Earth and it won’t be visible again until 2125.
Though the Perseid meteors appear to emanate from one area of the sky, the radiant, they can appear all over.
Instead of talking about stuff you can see in the night sky, here I want to talk about something that you can’t see – black holes. Since black holes are, well, black against the darkness of space and bend light around them, finding them is not easy. At the center of each galaxy, including our own, is a supermassive black hole. The Milky Way’s black hole is called Sagittarius A* and it’s only 31 times the diameter of our sun but contains 4 million times the mass of our sun. Fun fact, for the Earth to turn into a black hole, it would have to be compressed down to less than a cubic inch! These supermassive black holes are spotted by their effects on the stars and gas around them as it whips stars around at significant fractions of the speed of light and heats the gas into a glowing disk. Most typical black holes, however, are only three to ten times the mass of the sun. Some of these are undetectable and lurk in the darkness of space while other heat up nearby gas and emit x-rays that special x-ray telescopes can detect. So while the black holes themselves are invisible, their indirect effects are more easily seen.
The location of the supermassive black hole at the center of our galaxy. (You can’t, of course, see it.)
Get outside and enjoy the rare sight of multiple clear Ohio nights but be wary of the smoky haze. The earlier sunsets are also nice since we do not have to wait so long for the skies to get dark. Bring out a reclining chair as you patiently watch for meteors under the new moon. Bring some binoculars to view Venus and the Andromeda Galaxy.
Clear Skies!