HowDoWhy

What is the Milky Way?

Sunday, May 25th, 2008

If you ever find yourself far removed from the light pollution that saturates the city and suburban skies, take a look at the night sky and prepare to be impressed. Those of us who spend most of our lives in and around cities are often awestruck by how many stars there are out there once […]

What is a galaxy?

Wednesday, May 21st, 2008

A galaxy is a massive collection of stars gravitationally bound around a common central core. It is believed that most, if not all galaxies have at their core a super massive black hole - a black hole coming in at hundreds of thousands or billions times more massive than our own Sun.
Speaking of our own […]

What is a Black Hole?

Monday, May 19th, 2008

From some of my previous posts you know that objects don’t just have size, they have mass. A three-foot diameter ball of loosely packed feathers, for example, has far less mass than a three-foot diameter ball of lead. But if you keep compressing feathers into that three-foot sphere, keep squeezing and squeezing them in, you’ll […]

What is the closest star to the Earth

Wednesday, May 14th, 2008

We’ve already answered in a previous post that the Sun is the closest star to the Earth, but when most people ask this they’re really asking, what is the closest star to the Sun. The closest star to the Sun is Proxima Centauri at 4.2 light-years away.
Interestingly, most folks often think of Alpha Centauri as […]

How long is a light-year?

Monday, May 12th, 2008

You might be surprised to know that a light-year is just one normal Earth year long (a Julian year of 365.25 days)! Confused? Think of it this way, a light-year isn’t a measure of time, but a measure distance within a certain amount of time (a year).
If you’ve kept up with all my other posts on space, you’ll know […]

What is the speed of light?

Saturday, May 10th, 2008

After years of “close” estimates, the speed of light was nailed down to 299,792.458 kilometers per second or 186,282.397 miles per second in 1983. Previous estimates came surprisingly close to the mark given how difficult it must be to put a limit on something as fast as light. We also know that the speed of […]

How big is our solar system?

Wednesday, May 7th, 2008

Measuring the dimensions of our solar system brings up a question of preference. Are you interested in the diameter from the Sun to the outermost planet? To the innermost edge of the Kuiper Belt? To the outermost edge of the belt? To the Oort Cloud? Would you fully grasp the true scale even were I […]

What is an Astronomical Unit? How big is an Astronomical Unit?

Wednesday, May 7th, 2008

When dealing with measurements on an orbital scale, you have to think big. As my previous astronomy posts have shown, the distances are vast. Though humans see and use numbers like million, billion and trillion all the time, our brains have a tough time conceptualizing what those numbers really translate to. How often, for example, […]

Are black diamonds rare? Are they expensive?

Friday, May 2nd, 2008

What is this question doing in the middle of my Week of Astronomy? Well, stay with me and you’ll find out! Kathleen of Virginia asked this one, maybe as a hint to her husband?
Kathleen – Black diamonds, also known as Carbonado, are indeed rare in the same sense that any gem is relatively rare compared […]

What is a solar system?

Friday, May 2nd, 2008

With all this talk about stars, planets and moons in previous posts, it’s about high time I mentioned a solar system. A solar system is exactly what the name implies - the system associated with a sun (star). Our own solar system contains 8 planets. We once had nine but the planet Pluto was downgraded […]

What is the biggest planet in our solar system?

Friday, May 2nd, 2008

Mighty Jupiter is the largest planet in our solar system with a mass 318 times that of the Earth. In fact, its mass is more than twice that of all the other planets in the solar system combined. Aside from mass, the planet also takes up a lot of space. It is 88,736 miles in […]

There were 9 planets. What happened to Pluto?

Thursday, May 1st, 2008

Poor Pluto. Discovered in 1930 by Cylde W. Tombaugh, Pluto was thought to be the missing planet theorized to exist based on inaccurate calculations. It was added as our ninth planet and actually sparked quite a fan following with its popularity, even inspiring the name of a famous Disney character. For 36 years, humble little […]

How many planets are there in our solar system and what are their names?

Thursday, May 1st, 2008

There’s a lot more to our solar system than the planets. I’ll cover some of the less known objects and phenomenon such as the Oort Cloud, Kuiper Belt and other strange stuff in a future post, but when people think solar system, they usually think of the planets in orbit around the Sun. Our solar […]

How big is the Earth?

Wednesday, April 30th, 2008

There are several things in our solar system bigger than the Earth; the Sun and all the gas giants like Jupiter. But of the four terrestrial planets - the rocky worlds you could actually walk on if appropriately attired (Venus has a strict jacket and tie requirement) - the Earth is the largest. You have […]

How far away is the Earth from the Sun?

Wednesday, April 30th, 2008

The Earth circles peacefully around the Sun at about 149 million kilometers or 92.75 million miles on average. Our orbit is slightly elliptical so our distance swings from anywhere as far as 94.5 million miles and as close as 91 million miles. There are a lot of interesting facts about the Earth I’ll save for […]

What is a planet?

Tuesday, April 29th, 2008

Our solar system has an interesting and diverse cast of characters. We even have a black sheep in our solar family in the form of Pluto and at the center of all the recent controversy about its status has been one surprisingly difficult question to answer - what is a planet?
You’d think that pretty much any […]

How many times would the Earth fit in the Sun?

Monday, April 28th, 2008

I considered answering this in my previous post - How big is the Sun - but found the question so well answered elsewhere that I’ll give it its own post. The short answer is - 1 million. As explained by Ask an Astrophysicist at NASA’s Goddard Space Flight Center - Imagine the Universe, it helps […]

How big is the Sun?

Monday, April 28th, 2008

The Sun is about 1,392,000 kilometers or 875,000 miles across. If you wanted to put a belt on the sun to hold up its pants you would want to know its circumference and for that you just apply a little math. The circumference of a sphere is determined by multiplying 2 times pi (3.14) times […]

How old is the Sun and how long will it live?

Monday, April 28th, 2008

The Sun is about 4.57 billion years into its main-sequence stage and when we think of its age, that’s the number generally agreed on. You can think of this as the relatively stable period in a star’s life after it forms and during which it converts Hydrogen into Helium in a process known as nuclear […]

What is the Sun and what is it made of?

Monday, April 28th, 2008

If you’re ever away from the glare of city lights on a cloudless night, take a look up into the sky and marvel at the countless thousands of sparkling stars you see up there. Pick one you like and point your finger at it. Now imagine that maybe, just maybe, the star you’ve picked has […]

How far away is the Moon?

Thursday, April 24th, 2008 Today, the average distance to the moon is 238,856 miles.
There are two interesting things to note in that answer. First, note the word “average.” Remember that the Moon’s orbit is elliptical and not perfectly circular so the distance varies by as much as 26,000+ miles. To put that into perspective, the distance of the Moon […]