amateur astronomy Archives - The Spacewriter's Ramblings

I wrote the other day about city stargazing and general skygazing. That article got some nice responses from people who sometimes battle light pollution in their night skies. It’s a problem in many places on Earth. However, unless you are stuck in the middle of downtown “Big City”, there’s usually at least something you can observe. Light pollution isn’t the only challenge, as one of my correspondents pointed out.

Safety is also a challenge in some places. Obviously, wherever you gaze from has to offer a safe environment. I’m not just talking about safety from other people, however. Some sites offer physical challenges such as wild animals or terrain. Some years ago, I did some observing at a friend’s house high in the Rockies. Our biggest challenge (after the Denver Nebula) was the chance of stumbling across a foraging bear in the darkness. Of course, the bears are often more afraid of us. However, in the spring, when they’re hungry, they’ll take a chance on anything to get a bite to eat. Not that they eat stargazers, but we get in their way, sometimes.

I remember once going to the Grand Canyon and doing some night-time stargazing from a canyon overlook. There wasn’t a railing or anything to protect someone from going over the edge. Actually, I’m surprised more people don’t get hurt wandering around in the dark there. Then again, many areas along the rim are now “well-lit”. So there’s less chance of falling off a cliff (and, unfortunately, seeing a completely dark sky).

Other Skygazing Challenges

Beyond important issues of safety, sometimes the biggest challenge to effective stargazing isn’t a bright light or a hungry ursinid. For beginners, it’s often a lack of knowledge of what to look at in the sky.

One advantage that city stargazing has: is that it blocks out a lot of dimmer objects. It allows only the brightest to shine through. So, you know before you go out that you’re only going to see the eye-grabbers. Luckily, those appear prominent in most star maps and charts. The planets and Moon are good examples. You can’t miss those bright objects, especially the Moon. And, you can do lunar exploration with good binoculars and a relatively small and inexpensive telescope (on a good mount). I know skygazers who are so taken with the Moon that it is their main “go to” object. And, it’s out in the daytime during part of the month, so that gives you extra time to explore its features.

Use starcharting software such as Stellarium (screenshot shown here) to check out where objects will appear in your sky on the nights you want to stargaze.

Planets are much farther away. They also present the same challenge to both city and country stargazers: getting a good-enough view that you can make out features. For Mars, Jupiter, and Saturn, that does require a decent telescope. I’ve seen some remarkable views of Saturn, for example, from New York’s Central Park area, even with bright lights nearby. And, I remember seeing Comet Hale-Bopp from a brightly lit pier in Boston in 1997. So, some things are doable, even from the city.

Regardless of what you want to see, it is really helpful to do a little “ground school” before you head out. Learn to read star charts, check out the pages of the astronomy-related magazines for charts and stargazing directions. There’s a wealth of information that pops up if you search on “stargazing” or “what’s up in the sky?” That advance prep pays off under the starry (and often light-polluted) sky in the evenings or early mornings.

Just Do Skygazing

Another key to effective stargazing, no matter where you are, is to figure out what you really want to spend time chasing down. If it’s the Moon, you’ve got a wealth of treasures to check out. Planets provide a bit more of a challenge, and even if you live in a light-pollution jungle, you can still check them out.

Yes, getting equipment is challenging, too. It’s expensive. And, in these days of unemployment and COVID-19-related job losses, getting that telescope or binoculars you dreamed of may be a deferred pleasure. But, maybe a local astronomy club would welcome you as a “guerilla gazer”, by sharing views through their telescopes. It’s worth checking out. And, when planetariums and science centers re-open up, their “public nights” will again provide a nice view of the sky.

Unless you’re facing really awful weather where you live, now’s a great time to take up stargazing. Or, if you’ve stopped, it’s time to resume it. . Skygazing provides perspective. It gets you out of the house and off to another realm. If you share it with someone (a lover, a child, a parent, a friend), that simply doubles the enjoyment. Try it!

There’s a planet out there, orbiting a star. There are, in fact, many of them out there. Thanks to studies made from ground-based observatories as well as such orbiting telescopes as HST, Kepler, TESS, and others, we know about thousands of them. We know they’re there. We know that some are hot Jupiters. Others are more Earth-type worlds. Some are gigantic ice giants like Neptune or Uranus. There are direct images of such worlds, but they’ really don’t show us surface characteristics. Those types of images may come someday. For now, we’re limited to detecting worlds and characterizing them based on spectral studies or direct imaging. That’s how we get knowledge about their orbital positions and information about their stars.

Why study these worlds? There’s a lot we are still learning about our own solar system. Its history and evolution are still a story to be filled in with data. Looking at other planetary systems gives us a look at our own in different stages of development. It’s a bit like looking at a forest and seeing trees in different stages of growth. There are stars and planetary systems in our neck of the galactic woods. So, there’s very likely a good example of planetary collections at all stages of life

The Lens of Gravity

Finding worlds around distant stars is hard. They’re small and dim, compared to their stars, which are large and bright. Astronomers use all kinds of techniques to spot them. To me, one of the more interesting ways is via gravitational lensing, which sounds weird but is perfectly natural. It needs an object with a strong gravitational pull to pass in front of a more distant object. Gravity warps space. Anything that moves through warped space is affected. So, a beam of light from a more distant object that passes through the warped gravitational space around a foreground object looks warped. In more practical terms. the image of the more distant object looks warped. That’s because the light’s path is warped like a funhouse mirror by the gravity of the closer object.

Lensing History

I first learned about gravitational lensing as it relates to looking at very distant objects, such as quasars. Their light passes through warped space, and the effect can be downright eerie. The Einstein Cross, for example, is the light from a single quasar. That light gets warped as it passes through the gravitational pull of a galaxy cluster closer to us than the quasar. The result: a “cross” made of four images of the single quasar. Those images are created by the lensing effect of the galaxy cluster.

So, if that works for more distant, bright objects, can it work for closer, smaller, dimmer objects? It turns out it can. And, astronomers have known this for quite a while.

A Small Planet Caught in a Lens

Viewing a star with a Neptune-sized planet using the gravitational lensing technique via an artist’s concept. The inset shows the star and planet in detail. Courtesy: University of Tokyo.

For example, a couple of years ago, an amateur astronomer spotted a gravitational lensing event that involved one star passing in front of another star. Now star-star lensing events are understandable but still rare. While there are a lot of stars in a galaxy, the chances of one passing in front of another from our point of view are still low. Space is big and not as “packed” as we’d like to think in most places. So, finding one of these is kind of an astronomical jackpot. Data from the event can give information about both stars.

Anyway, the observer, named Tadashi Kojima (from Japan), spotted this event and immediately sent out an alert. Pretty soon everybody was checking it out. That included astronomers at the big observatories. It turns out that the lensing event also showed that the foreground star has a planet in orbit. Astronomers from the University of Tokyo observed the event using telescopes around the world for more than three months. The data they collected about the star and its planet was fascinating. For one thing, the star is about half the mass of our Sun. Its planet is more massive than Neptune, but orbits at the same distance as Earth does from the Sun. It’s also a relatively close neighbor, lying about 1,600 light-years away. The more distant star was about a thousand light-years more distant.

What Does it Mean?

We are so accustomed to OUR Uranus and Neptune-type planets out in the distant reaches of the solar system. Sometimes that leads people to think that ALL solar systems have their giant planets out in the boonies. But, as planetary scientists study more of these exoplanet systems, they find giant planets in remarkably close orbits. That leads to questions about where ours formed in the early protoplanetary nebula. If they formed close in, then why are they now out in the solar system sticks? Studying more stars with giant planets close in can help answer those questions for our own solar system. This particular discovery also tells astronomers that more Neptune-sized planets orbit close to their stars at some point in their evolution.

So, gravitational lensing, which has been an observational tool for years now, is rooting itself firmly into the toolbox of planetary detection methods. It’s a perfectly useful way to peer at distant objects and get major data about them. Ultimately, it all comes back to help us understand how and why the universe works in ways both big and small.

The Spacewriter's Ramblings

Category Archives: amateur astronomy

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