Things that go flash in the night

It's a bird, it's a plane, its...a speck of dust?  That's right, that beautiful shooting star you were just exclaiming about was actually a tiny speck of dust meeting its fiery end as it slammed into Earth's atmosphere at around 40 kilometers per second.  Anything flying through the atmosphere at speeds that high is heated to thousands of degrees by friction with the air, causing it to glow and, in the case of small things like our dust speck, burn up.  Every now and then you might get lucky enough (or unlucky enough, depending on the circumstances) to see something larger slam into Earth's atmosphere.  Rocks the size of baseballs and basketballs produce fireballs that may last for tens of seconds as they streak across the sky.  I've been lucky enough to see a handful of these in my lifetime and every one was absolutely spectacular.

There are a number of phenomena that "go flash in the night", with shooting stars, formally known as meteors, being among the more common.  The Earth actually gets hit by some 300 tons of space rock every day.  Most of that is in the form of dust and most of that hits over the oceans (due to them covering the majority of the Earth's surface).  The good news is, the larger the space rock the less frequently they tend to hit us.  It takes a rock several tens of meters across to do any significant damage, and those only hit us about once every few hundred years.  "Armageddon" rocks are once in 100 million year events.

Another common flash in the night has origins much closer to home, namely satellites.  Watch the night sky for even 10 minutes and you're likely to observe at least one satellite.  Satellites look like stars that are steadily moving across the sky.  You can tell satellites apart from airplanes because airplanes blink and satellites don't.  A few satellites are really spectacular.  A group of satellites called Iridium communication satellites were put into orbit in the 90's to provide satellite phone service.  The antennas of the satellites are particularly reflective, and when hit with sunlight just right, will become very bright (brighter than any star in the sky).  This is called an iridium flare and can be identified by the way the satellite starts off very dim, then becomes very bright for a few seconds before dimming again.  Another very spectacular satellite is the International Space Station (ISS).  Due to it's size, the ISS is incredibly bright - unlike an iridium flare, it will maintain its brightness the entire time it is visible.  You can find out when the ISS will be visible in your location by going to http://spotthestation.nasa.gov/sightings/index.cfm#.U9RBAfldXRM.

Movies often incorrectly portray comets as flying across the sky much like fireballs.  Comets are actually much more subtle - they slowly grow brighter over the course of weeks and they slowly fade away, all the while moving across the sky at a pace that can only be observed by watching the comet for many days.  So comets really can't be described as something that "goes flash in the night"; however, they are directly related to another "flashing" phenomenon - meteor showers.

A meteor shower results when comet leaves behind a trail of dusty debris that happens to lie in Earth's path as it orbits the Sun.  When the Earth flies through the debris, the result is lots of shooting stars over a period of one or more nights - a meteor shower.  There are several meteor showers that happen at the same time each year - The Perseids are a regular August meteor shower that peaks the night of August 12 and is often one of the best showers of the year.  Unfortunately, this year that coincides with the full moon, making the sky much brighter and the meteors harder to see.  The Orionids are a good October meteor shower and the Leonids are another of the best showers of the year and peak in November.  Both of these will have little-to-no moonlight interfering.  The best time to observe a meteor shower is between midnight and dawn, and the best approach is to find a dark location with a good view of the sky and to lay back and observe as much of the sky as you can - meteors will happen all across the sky.  No instruments needed!  Actually, telescopes will hinder your ability to observe shooting stars because they only allow you to see a tiny piece of the sky.

But remember, it doesn't have to be a meteor shower to observe shooting stars and other flashy phenomena!  Get outside and start looking up!

How to buy a telescope, part 1

[This is long, so I'll break it into two parts - part 1 will focus on the basic characteristics of telescopes in general, while part 2 will look at specific telescope designs and reasons why you might choose one over the other.]

So we enjoyed a few days of spring weather before winter returned with a vengeance, so now, short of pulling your skis back out of storage, there's not much to do but browse astronomy magazines pondering which telescope would look best next to your patio furniture.  If you are indeed browsing telescopes in an astronomy magazine you're already well ahead of someone exploring the telescope aisle at "Buy'n'large" (if you don't know what I'm talking about, watch the movie Wall-E).  The fact is, you should never, ever, buy a telescope from a department store.  In a large city, you might be able to find a store (typically a camera store) that carries and is knowledgeable about quality telescope equipment, but otherwise, the internet is your best bet.

Let's consider what you should look for in a telescope.  First, some telescope basics.  In astronomy, there are two primary reasons to use a telescope:

1. Collect more light:  A telescope is essentially a "light bucket".  Most astronomical objects are fainter than the eye can see, so a telescope is used to collect more light and thereby allow us to see them.  Just as when you want to collect more water, you need a bigger bucket, when you want to collect more light you need a bigger telescope.  Telescope size is defined as the diameter of the largest mirror or lens (called the "primary" mirror or lens) in the telescope.  In the same sense as animals that need to see in dark conditions (such as squid or owls) have giant eyes, telescopes with giant lenses or mirrors will allow you to see much fainter astronomical objects like nebulas and galaxies.  Trust me, these are the things you want to see.

Andromeda galaxy viewed through a smaller telescope (a), and a bigger telescope (b).  The view through the bigger telescope allows the faint spiral arms to be seen.

2. Resolve fine details:  When you look at those amazing photos taken by the Hubble Space Telescope, one of the most awe inspiring characteristics (aside from the colors, and we'll talk about that in a bit) is the fine detail in the images.  Being able to resolve fine detail allows you to pick out individual stars in a globular cluster, see small craters on the moon, and distinguish wisps of gas in a nebula.  Having a telescope with good resolution is the difference between the cell phone camera you have today, and the one you had 10 years ago.  The resolution of a telescope, like light-collecting power, depends on the size of the telescope, and again, bigger is better.

Andromeda galaxy viewed with increasing resolution (a - d).  The view through a larger telescope (d) allows finer detail to be resolved.

There are several misconceptions about telescopes, and these are often played up by department store telescopes in an attempt to attract the unwary customer.  The first and most abused is magnification.  Many people believe telescopes behave similarly to microscopes, in that they magnify images.  There are two key differences between a telescope and a microscope - objects observed in a microscope are well illuminated, while telescope targets are faint, and objects observed in a microscope are very, very small, while telescope targets generally are not.  As a matter of fact, most of the objects we would want to observe in a telescope appear relatively large in the night sky.  A classic example is the Andromeda galaxy which is as large as the full moon in the sky, but hard to see because it's so faint.  In contrast, the smallest objects in the night sky are stars, and they're not hard to see at all!  The problem with magnification is that bigger is not always better, in fact, too much magnification can actually make an image much worse especially if you are viewing with a very small telescope - blowing up a faint, fuzzy image does not make it better!  The other thing department store telescope ads fail to mention, is that you can change the magnification of a telescope by changing the eyepiece - an accessory that can be purchased after you've found the perfect telescope for you.

A little magnification is good, but too much magnification may make your image worse.

The second misconception is that when you look through a telescope you'll see colorful images just like the Hubble pictures.  In general this will not be the case.  Our eyes have two types of light detectors in them - cones, which detect color, and rods, which are sensitive to faint light.  When viewing faint things, like objects in a telescope, only the rods are activated, allowing us to see the objects, but not their colors.  This is also why you don't see colors in a dark room.  In order to see color in astronomical objects, they must either be bright (like Jupiter or the double star Albireo) or you must take a long picture of them.  Photographs pick up color because long exposures allow them to collect more light.  And remember, the Hubble pictures are photographs too - often with much processing to enhance colors.

At this point you should have the idea that you want to buy the biggest telescope you can afford.  This is mostly true, but you also want to make sure you get a good telescope and that you get the right telescope for you.  We'll focus on the second point in part two, but I will include a list of reputable telescope brands below (note that this is not an all-inclusive list and I apologize if I leave out your favorite brand).

Generally reliable telescope brands (in no particular order, but the top 3 cater more to first-time buyers):
Meade
Celestron
Orion
Losmandy
Levenhuk
Astro-physics
Takahashi

Small telescope sights

Returning home from orchestra this evening it was all I could do not to drive off the road.  No it wasn't icy or snowing - it's actually a beautifully clear night, and therein lies the problem:  it's hard to drive and try to pick out a constellation at the same time.  "...no officer, I wasn't texting - I was stargazing."

We must be approaching spring because it's one of those rare nights when it's not only clear, but relatively warm (as in, above 20 degrees Fahrenheit).  It turns out my back yard is an excellent stargazing location - quite dark and unobstructed.  I was so inspired, I decided to drag my 4" Newtonian telescope out into the yard to check out some of my favorite winter sights - there are some great objects for viewing in a small telescope or binoculars up right now.

I started with the Moon - a thin crescent in the western sky.  With binoculars or a small telescope it's possible to see craters and mountains on the moon in fine detail.  In its crescent phase the moon is a special treat because you can not only see the illuminated crescent, but also the dark side of the Moon.  Along the terminator line (the boundary between the light and dark sides) craters stand out in crisp detail.  I played a bit with taking pictures through the telescope with my cell phone camera - not ideal, but it's possible with some careful positioning.  The picture below really doesn't do the Moon justice, but you can clearly see several craters along the terminator, and even one crater with a distinct mountain in the middle.  The Mars Curiosity rover is currently visiting a similar crater on Mars.

Picture of the Moon taken with a cell phone camera through a 4" Newtonian telescope

After the Moon, I turned my telescope towards Orion and pointed towards the sword.  With either binoculars or a telescope, or even the naked eye from a dark location, the middle star in Orion's sword (a vertical line of stars hanging below Orion's belt) appears as a fuzzy patch.  This "star" is actually a nebula - a cloud of gas and dust where new stars are being born.  A little careful observing with a small telescope will reveal that one of the bright stars in the nebula is actually several stars very close together - good eyes or a larger telescope will reveal these to be four bright blue stars in a square, called the trapezium.  I tried to take a picture of the Orion nebula with my cell phone, but faint objects are very hard line up and focus!  A better approach is a real camera mounted on a tripod with the exposure set to 10 seconds - an SLR camera with lots of manual settings is ideal, and digital is best because you can take lots of pictures and experiment with settings.  Here's a picture I stole from someone else.

The Orion Nebula as seen through a small telescope.  Picture from http://www.ericteske.com/2014/02/complete-ias-noviceurban-observing-list.html

Moving on, I swung the telescope up to Jupiter, almost directly overhead.  Through binoculars or a small telescope Jupiter appears as a bright disk with four tiny stars arrayed in a line to either side.  Those tiny "stars" are actually Jupiter's four largest moons - Io, Europa, Ganymede, and Callisto - called the "Galilean moons" after Galileo, who discovered them the first time he looked at Jupiter through a telescope.  A bit of patience looking at Jupiter and you may also be able to discern two red bands stretching across the face of Jupiter's disk - these are actually red clouds in Jupiter's atmosphere.  I took a picture of Jupiter and you can distinctly see the moons, but unfortunately the atmospheric bands didn't show up.

Picture of Jupiter taken with a cell phone camera through a small telescope.  The splotch to the right of Jupiter is a reflection on the lens of the telescope.

I may have looked at the Moon, Orion's nebula, and Jupiter hundreds of times through telescopes as big as 30" across, but I still never tire of seeing them.  As a teenager with a 2" telescope set up on my porch, they were among the very few objects I knew how to find, and I would look at them night after night, amazed by these distant worlds.  You don't need a giant telescope to appreciate the night sky - a pair of binoculars is enough to see the Universe in a whole new light.