Ask an Astronomer!

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Previously Asked Questions

Answers provided by Neil Comins

How would creatures determine time in scenario like Earth with a colder sun? If it’s always day time would they never sleep? What other systems in nature could be used to determine relative difference for passage of time?
Wonderful question!  Most living creatures on Earth evolved “biological clocks” synchronized with Earth’s day-night cycle.  However, above 78 deg N latitude and below 78 deg. S latitude, there are periods of daylight and night far longer than 24 hours.  Animals living in these regions have more complex “biological clocks” than the rest of us.  Their bodies respond more to internal stimuli to drive their “day/night” cycles.  In other words, different parts of their bodies tell them what they need to be doing, including sleeping.  Our bodies have some of those stimuli, such as being hungry.  So, I would suggest that life would evolve on Earth with a colder sun would have more complex, self-driving (rather than being driven by the Sun) biological clocks.  If any teachers or advanced students are interested:

It makes sense how the moon affects tides, but why does the absence of the moon speed up the wind? Is it kind of like waves made of air that would simply be bigger because the water gets pulled more drastically higher and lower? How might this affect precipitation processes? Should the wind be slower or missing entirely on Earth with Two Moons?
Very complicated issue: The faster winds would be the result of the planet rotating faster than Earth.  So it would have a different day/night (or heating/cooling) cycle than our Earth.  This would lead to different wind patterns, which are driven in large part by heating and cooling of the planet and the air.  This would also have an effect on precipitation.  Because weather prediction is among the most complicated areas of mathematics, it requires incredibly complex computer simulations to provide meaningful results. The details  could only be worked out if long simulations of a more rapidly rotating earth were carried out.  To the best of my knowledge, this has not been done.  My results in the book were based on short simulations provided by meteorologists.Do the orbital planes differ in axial tilt for each moon in the Two Moons scenario? If they did how might it alter the conditions on the planet or each moon?

I assumed the orbital planes of the two moons were the same.  If the planes of the orbits of the two moons were different, that would create a much more complex dynamic.  Depending on the amount of axial tilt, the two moons could interact so that one of them crashed into the Earth and the other was flung away, or they could have developed very elliptical orbits more quickly than they would co-rotating.  This would lead them to colliding more quickly than otherwise.  I expect that different axial tilts would lead to an interesting array of different dynamics.  These would have to be simulated as “three body” problems, including tidal distortion for all three bodies.

I noticed the moon was HUGE, orange and hanging very low in the sky tonight coming back from the grocery store around 11pm. I thought harvest moons are only in October – the internet doesn’t indicate it’s anything special tonight – is this a frequent occurrence??

Whenever the Moon is low in the sky, light from it (scattered sunlight) passes thru a lot of air in our atmosphere.  The more air the light passes thru, the more violet, blue, and yellow light from the Moon is scattered in our atmosphere.  As a result, the light arriving to our eyes directly from the Moon looks redder (i.e., orange) than usual.  That holds every day.  However, when the Moon is full, as it was recently, the effect is more noticeable.  Furthermore, when the Moon is low in the sky, our brains compare its size to objects on the Earth, which gives it a larger apparent size in our minds.  More at

I’ve combed the net trying to find this answer, but am at an absolute loss. Hope you can help. What is Turner 5 in Orion’s Arm? Is it a star, does it have planets around it? I’m writing a sci fi comedy set in Orion’s Arm (on the outer edges of it), so I’m really looking for known stars and planetary systems. Thank you in advance.

Turner 5 is an “open cluster” of several hundred stars. It is virtually certain that most, if not all, of these stars have planets orbiting them. An open cluster is a group of stars that formed together, but which are drifting apart. The Sun was likely formed in an open cluster. I hope this helps!

If we are seeing Andromeda as it was 2.5 million years ago, how can we actually know that it is 2.5 million light years away given that it has traveled some distance within those 2.5 million years? If we are seeing a “ghost” of its past, are we not also seeing a “ghost” of its actual distance and location?

Great Question!  We know Andromeda was 2.5 million light years away when the light we see was emitted, because there are events, such as exploding stars, occurring there.  We know that certain exploding stars all reach the same maximum brightness.  Comparing the known maximum brightness of those exploding stars in our Milky Way to the brightness we see of those exploding stars in Andromeda, there is a simple algebra equation we can use to determine how far away they (and the galaxy they are in) are from us. So, we are seeing light from Andromeda that was emitted 2.5 million years ago when it was 2.5 million light years away from us. Andromeda is no longer 2.5 million light years from us, as you suggest.
Since that light was emitted, Andromeda and our Milky Way galaxy have been moving toward each other.  Therefore, if we could instantaneously measure the distance between the two galaxies, Andromeda would be less than 2.5 million light years from here today.  We can’t do that, of course, but we can measure the speed at which the two galaxies are approaching each other using the Doppler Shift measurements of light from stars in Andromeda.  Doppler shift is the change in wavelength of light (or sound) that is moving toward or away from us.  Andromeda is approaching us at a speed of about 250,000 mph.  Every year, Andromeda gets about 2.2 billion miles closer to us.  As a result, the two galaxies will collide in about 4.5 billion years.  By analogy, the Sun is about 8 light minutes away from us, so we see it as it was 8 minutes ago.  If it were to suddenly be destroyed (which it won’t be), we wouldn’t know for another 8 minutes. I hope this helps!

How difficult was it to obtain a job in astronomy and how many years did it take you to achieve it?

In order to obtain my job as a professor of astronomy at the University
of Maine, I had to obtain a doctorate (Ph.D) in astronomy. The route to a
doctorate is first to get an undergraduate degree (in my case a Bachelor of
Science or B.S.), which takes four years. Then I earned a Masters degree
(Master of Science or M.S.), which took me 3 years. Finally, my Ph.D. took
another three years, so that was a total of 10 years of college. In order to
show that I was qualified to do research in astronomy, I had to publish
several research papers in what are called “refereed journals.” These are
journals in which established scientists review the papers before they are
published and recommend that they be accepted, rejected, or modified and
then accepted. I also gave talks to other scientists, including Stephen
Hawking at Cambridge University. Many other people who become
professors of astronomy take up to 4 extra years in positions called postdocs,
before becoming professors.

What would you say is the biggest skill you need in order to become an astronomer?

The biggest skill I needed to become an astronomer is the ability to do
a lot of different kinds of math. Mathematics is the foundation of much of
astronomy and all of astrophysics. Astrophysics is work to derive and
explore the equations that describe astronomical objects. I do both
astronomy and astrophysics.

In what field of astronomy do you currently work?

I work in several areas: I study the evolution of galaxies like our Milky
Way using computer programs to simulate the motion of stars and other
matter in the galaxies; I study the evolution of stars with planets (called
exoplanets), also using computer simulations; I study the effects of Einstein’s
general relativity on stars; and, in the realm of science education, I study
misconceptions people have about astronomy, their causes and how to
replace the misconceptions with correct information. Finally, I help other
educators incorporate astronomy information in educational tools, such as
Minecraft and various planetarium shows. My hours are extremely flexible.
Except for the 6 hours of classroom time each week, and an occasional hour
of meetings every few days, I can spend my working time as I see fit.

What is the most difficult part about being an astronomer in your daily life?

The most difficult part of being an astronomer in my daily life is leaving
my work at the office, so that when I come home I can focus on family
things. One fun fact: if you Google “Chandrasekhar Nobel Lecture”
and then look at Chandrasekhar’s lecture on The Nobel Prize web site, you
will see that my early research was cited in a Nobel Prize.