As an astronomy teacher, variable star observer and host for public nights at the observatory, I have a variety of interesting experiences. What good are experiences if your don’t share them?

My students are a wonderful source of insight and entertainment. My colleagues are constantly challenging me to be better. And the stars are calling my name.

The name of my blog comes from Chet Raymo, a former professor of physics and astronomy at Stonehill College. In his book *Skeptics and True Believers*, Raymo paints a metaphor of science as an island of the sea of mystery. The power of this metaphor, according to Raymo, comes from the facts that 1) the universe is effectively infinite, and 2) our brains are finite.

You can read more from Raymo at his blog (now ended and archived) “Science Musings.”

**About the Header Image: M66 (NGC 3727) is a galaxy discovered by Mechain before 1780. M66 is 6.6 Mega-parsecs (about 21.5 million Light Years) from us. M 66 exhibits great dust lanes and spiral arms. To be found in the constellation Leo, M 66 is part of a group of interacting galaxies known as the Leo Trio. **

### Like this:

Like Loading...

Thanks for you comment on my blog post “Transit of Venus” as you may have guessed I hit the publish button when the post was 25% complete.

The Science Geek

http://www.thesciencegeek.org

LikeLike

Hello Mr. Hands, I was watching your periscope where you said we could leave questions on your blog. I hope I am doing so in the right place. I did try to ask the question on your periscope, but I’m not sure you got the gist of what I was asking.

I’ve been reading up on the Drake equation and yes, while I understand it wasn’t initially meant to calculate an actual number, but rather steer us towards criteria for further research, I am trying to wrap my head around the math.

I am looking at the original version of the equation stated as: N = R* x fp x ne x fl x fi x fc x L

Now, R* is not the total number of stars in the galaxy but rather the rate of star formation, expressed as the number of stars formed per year.

If we want the formula to spit out a value of the number of civilisations present in the galaxy at the present time (N), we would have to multiply R* by a value of time. I would think that R* x age of the galaxy would return the total number of stars in the galaxy, and this would be the starting point for the multiplication of all the other fractions that follow in the rest of the equation.

However, R* is not multiplied by the age of the galaxy to give the total number of stars. The only variable of time that it is multiplied by is L which is the length of time a civilisation tends to broadcasts signals for, until it becomes radio-silent.

It seems to me that something is missing here. Are we only looking at civilisations that originated during the past L years?

Am I making any errors in my reasoning or overlooking something? Please help!

Thanks,

Reiad

LikeLike

Dennis, can you tell me when you look up at a star, why does it appear that it is twinkling? Thank you

LikeLike

Michael, I’ve noticed that when looking at a planet with my unaided eyes, it does not twinkle. Even though stars are much larger than planets, stars are also further way, so they appear as points of light. As that stream of photons come through Earth’s atmosphere, it gets blown around a little by our wind, making the star appear to twinkle. Planets present a disk to our eyes, and even though that light also gets blown around a bit, there’s mostly overlap with the light reflecting off the rest of the disk. That makes planets appear to not twinkle.

Dennis

LikeLike

Hello Mr. Hands, I was watching your periscope where you said we could leave questions on your blog. I hope I am doing so in the right place. I did try to ask the question on your periscope, but I’m not sure you got the gist of what I was asking.

I’ve been reading up on the Drake equation and yes, while I understand it wasn’t initially meant to calculate an actual number, but rather steer us towards criteria for further research, I am trying to wrap my head around the math.

I am looking at the original version of the equation stated as: N = R* x fp x ne x fl x fi x fc x L

Now, R* is not the total number of stars in the galaxy but rather the rate of star formation, expressed as the number of stars formed per year.

If we want the formula to spit out a value of the number of civilisations present in the galaxy at the present time (N), we would have to multiply R* by a value of time. I would think that R* x age of the galaxy would return the total number of stars in the galaxy, and this would be the starting point for the multiplication of all the other fractions that follow in the rest of the equation.

However, R* is not multiplied by the age of the galaxy to give the total number of stars. The only variable of time that it is multiplied by is L which is the length of time a civilisation tends to broadcasts signals for, until it becomes radio-silent.

It seems to me that something is missing here. Are we only looking at civilisations that originated during the past L years?

Am I making any errors in my reasoning or overlooking something? Please help!

Thanks,

Reiad

LikeLike

Reiad,

Thanks for your question. You are going deeper into this math than I have and I thank-you for inviting me in on the ride. Let’s figure it out together.

In your 5th paragraph you write “we would have to multiply R* by a value of time.” Why do we have to? Isn’t time already included in that R represents the number per year? Does that “per year” do it?

Let m know what you think.

Dennis

LikeLike

Dennis, Thank you for answering the ‘do photons have mass’ question during your 8/22 scope. Gravitational lensing has been confusing me for some time and still does if I’m honest. Clearly a photon doesn’t have mass because if it did it wouldn’t achieve the speed of light but if it doesn’t then why is it bending? So the answer lies in spacetime. Now I just need to understand spacetime!!

I asked this question during your 8/3 scope (43:40) after you referred to the article about light bending in your mag. but someone else give me the wrong answer so I gave up. Luckily ‘Mike’ asked the question again and you responded.

Thank you again for taking the time to share your knowledge. I look forward to all your scopes, even if only on replay!

Kind Regards

Kevin Etheridge

LikeLike

Hello Mr. Hands

I recently sent you an email to your High Point University email and I was wondering if you have received it. It is in regards to a request for you to possibility give a presentation to my astronomy club. I really enjoy your Periscope talks and I think others would like to hear you speak about Astronomy. Thank you for your time.

Brandon

LikeLike