here’s a breathless announcement

It is a bit bigger and somewhat colder, but a planet circling a star 500 light-years away is otherwise the closest match of our home world discovered so far, astronomers announced on Thursday.

This comes from Scientists Find an ‘Earth Twin,’ or Perhaps a Cousin in the New York Times.

Here is something that bothers me in this story, and in some of the pronouncements of astronomer’s in general. The way this is reported, it sounds like they know for sure that what they saw is 1) a planet; 2) of a certain size; 3) orbiting a Sol-like star; 4) orbiting in the ‘habitable zone’ of that star. All of these pronouncements are stated matter-of-fact-like.

Yet what do they really know?

Kepler 186f is the latest planet to be sifted out of the voluminous data collected by Kepler, which kept watch over 150,000 stars, looking for slight drops in brightness when a planet passed in front.

Hmmm… “slight drops in brightness” equals a habitable planet.

I see how that works.

Is this the only possible explanation for a “slight drop in brightness,” no matter how regular it might appear to be?

Apparently this “planet” orbits its star in only 130 days, so presumably every 130 days the scientists observed similar drops in brightness. So… they know for sure that is a planet? Could be, but what if it were something else?

And this star is 500 light years away, so they say. So these slight drops in brightness are something that happened 500 years ago. But who is to say they continue to happen today? There is no way we can observe that data – no one will ever go there to find out, even if we could learn to travel at the speed of light (or faster).

No doubt there are things I don’t understand about this, but it seems pretty thin gruel to build a theory of the universe on. We see light in the universe through various means. We have theories about what that light means. But we have very little way of proving whether our theories are correct or not.

We call the lights in the heavens stars. We can analyze data about the light coming from what we call stars, and we form conclusions as to what those stars are based on observing similar data from the Sun. But we still don’t know for sure what those stars are or what all this data means.

What do we know for sure about the heavens? We know that God made them… whatever they are:

Genesis 1:16 God made the two great lights, the greater light to govern the day, and the lesser light to govern the night; He made the stars also.



  1. Mark Smith says:

    I have a PhD in physics and I teach astronomy, so I know a little about this. Astronomers know Kepler’s Laws of how things orbit one another. The Kepler satellite (named after the man Johann Kepler, who had a PhD in theology and was trained to be a Lutheran minister, who discovered the laws around 1609) looks for tiny objects that pass in front of stars, thus blocking the light from that star a bit in a regular pattern. After watching a star for years you can see if something is regularly orbiting it, and from Kepler’s 3rd Law figure out the distance of the planet from the star. From that same law you can deduce the physical size of the planet since you know how much it blocks the light.

    From the size of the planet and the distance of the orbit from the star you have a rough estimate of what the planet is like. If a planet is 1.1 the mass of the Earth, you know it isn’t a gas giant like Jupiter, for example. Also, you know it isn’t small like Mercury. Given that a planet formed, and hence there was lots of gas and dust floating around, you guess the planet has an atmosphere. If it is at the right distance, then liquid water could be present. This is all the case for this planet.

    NOW…in this case the media has jumped the gun on the story and made it sound better than it is. What I have explained is all they have. Likelihoods of an Earth-like atmosphere. But, there IS an approximate Earth mass planet there. We just don’t know about the atmosphere for sure. But the potential is there.

    Other telescopes can observe the spectrum of the light from planets (and I don’t know if they can from this one…500 ly is a long way) to verify that water is actually present.

    So, to wrap up, what do they KNOW:
    1) There is an approximate Earth mass planet around this star
    2) It is in the “Goldilocks” zone of the star, meaning water can exist in liquid form

    That is it. They don’t even know the density of the planet yet.

  2. Mark Smith says:

    Furthermore, we know more than you suggest about stars, and other objects in space. Stars emit light. They are hot and produce a spectrum that follows Wien’s Law. From that we get the temperature of the star. By carefully looking at the spectrum from a star, we see that it has an absorption spectrum. That absorption spectrum reveals a LOT about the star. From it we know the atom types in the star, their relative abundances, the magnetic fields of a star, how fast it rotates…lots of things. Our knowledge of stars is pretty solid. You don’t have to go touch one to know a lot about it. God made the light come to us…so we can study them that way!

    I appreciate that is difficult for “laymen” to respect or “trust”, but we really do know a lot about the universe like distances to objects, the speeds they move at, even ages. Of course, all of this is based on a scientific assumption, which is key. When I teach the definition of science at a public university, I define science as “a human endeavor that seeks explain natural phenomena with natural explanations”. So ages come out to 13.6 billion years for the universe, for example, if all that operated was natural processes. Of course WE KNOW FROM THE BIBLE that more than that was happening…

    • Mark, I appreciate the comments. I’m on my iPad, so awkward to type . I’ll respond with more later.

      Don Johnson
      Jer 33.3

    • Hi Mark,

      I agree, this is what we conclude from the data we receive, we analyze the light [spectrum and so forth], we apply known properties of light, and we make conclusions about what that means. I recognize that people like Kepler and Wien have observed what appear to be constants and therefore laws. Based on those laws, the conclusions drawn are reasonable.

      My point, however, is that we really have insufficient data to know everything about the universe. Our understanding of the laws could be incorrect, our interpretation of the data could also be incorrect. I talked to Danny Faulkner last fall (BJU grad, currently working with AiG, formerly professor at the University of South Carolina … some branch campus, can’t remember the location). He has a theory to explain the vast distances from earth of the stars and the challenge that presents to Biblical cosmology. I don’t remember all the details, but as he described it, my thinking was, “Well, it’s plausible, it follows the known laws of physics as far as I know, so it is a possible explanation.”

      But in the end, we don’t know. I suspect that when we get to heaven, if the Lord opens up these areas of knowledge to us, we will be surprised about what the reality is and how far off reality we were in our guesses. (Or perhaps, how close, in some cases.)

      Don Johnson
      Jer 33.3