By Greg Woolever, Ashton Observatory Director| Des Moines Astronomical Society | www.dmastronomy.com
Health concerns about COVID-19 have caused our Ashton Observatory north of Des Moines to be closed. We will resume normal public events once the pandemic is over. But what can families that want to do some stargazing do in the meantime?
Observe the Night Sky in Central Iowa
The exciting night sky is always up there, waiting for you to look up. There will also always be the normal challenge of clouds and weather. Things like high humidity, air pollution, particulates like pollen and dust, and air turbulence affect how clear your view is. So, to see well, you do want a clear sky. One helpful website for evaluating the conditions is HERE. Click the location nearest you to see a chart showing the current conditions for astronomy.
Or, you can just look outside and tell when clouds are gone. 😊One note – conditions can change quickly, and sunset can sometimes lead to clearing skies, so don’t give up too fast.
What You Can See in the City
From a city location you can only see the brightest stars and objects. Things like the Moon, and planets like Venus, Jupiter, Saturn and Mars are all easy to see under urban light pollution. And you’ll love what simple binoculars can reveal, even under urban lights. Can you find a planet, a galaxy, a globular cluster, a nebula?
Right now Jupiter and Saturn are rising at about midnight and will continue to be a highlight all summer long. They’ll rise about 4 minutes earlier each day [(24*60)/365≈4]. If you hold binoculars steady, you should be able to see the four brightest moons of Jupiter too. Some binoculars can be mounted on a camera tripod to really give you a steady view.
How to View the Milky Way
From an urban location you will not be able to see the Milky Way. To see the Milky Way and other deep space targets you need dark skies. The county park where Ashton Observatory is located is one convenient location – about 20 miles northeast of Des Moines. You can see the Milky Way with naked eye there if the sky is dark and clear and no moonlight. If you’ve never seen that before, it’s time to be amazed! The Observatory will be closed now but the yard near it is always open to the public. There may be other locations near you that are dark.
Star Charts & Stargazing Apps
Where the Milky Way is in the sky will change from hour to hour, and season to season. So how can you know where to look you ask? Great question! There are plenty of apps for smartphones that can show you that kind of information. One of the best is SkySafari. There are three versions of that app, but the basic version will be just fine for most folks.
Another good option for studying what’s in the sky is a printed star chart. Download them from their websites, free. The two best are here: SkyMaps, and Whats’s Out Tonight. They have a new chart every month because Earth’s travel around its orbit means the night sky is looking in a different direction as time passes [30 degrees per month since 360/12=30].
If you like making things with your own hands, one other way to identify the constellations in the sky is to make a planisphere. That will show you where the stars are on any date at any time. Download plans HERE.
And speaking of movement, once you start looking at the night sky, you will notice that everything in the sky is moving. Well, to be accurate, the targets are mostly not moving at all – YOU are moving as your planet, Earth, rotates. It’s that rotation that makes everything rise in the east and set in the west. If you watch the night sky for an hour, you’ll notice that everything moves 15 degrees per hour [360/24=15]. Check it out!
Phases of the Moon
Everyone loves looking at the Moon. Binoculars are a great tool for that. When you begin noticing what’s happening with the Moon, you’ll see that the part that is illuminated changes every day. That’s called phases. When the Moon is near the Sun, the amount that is bright is thin – called a crescent. When it is further from the Sun, more of the Moon is bright. When it is opposite the Sun (rising when the Sun is setting) it is a full Moon, and sunlight lights up the whole Moon. Eventually the Moon gets back even with the Sun, and a new lunar cycle begins.
So why does the Moon do that? It’s because the Moon’s orbit causes it to rise later each day – on average about 45 minutes later per day.
Do you only see the Moon at night? Can you ever see it during the day? If the phase of the Moon changes every day, does it change every hour? Every minute? Every second?
If you want to see lunar craters up close you’ll need a telescope – a magnification of 50x is plenty. Binoculars are usually about 7x, which is a great start, but if you want a little information about selecting a first telescope click HERE. But you don’t need to have a telescope to begin exploring the night sky.
Featured photos courtesy of the Des Moines Astronomical Society.