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15 percent of the planetary systems in the universe are similar to the solar system

The amount of solar systems similar to ours is estimated at about 15% of all systems in the universe. Despite this, the scientists are optimistic: "This will leave us with several hundred million solar systems that may be like ours."

Solar system - the planets are shown according to their relative size. NASA illustration
Solar system - the planets are shown according to their relative size. NASA illustration

In the entire universe, only 15% of the systems are similar to our solar system.

In their quest to find solar systems similar to our own, astronomers are determining how common such a system is in the universe.

About 15% of the stars in the galaxy have a planet system similar to ours, with several gas giants in the outer part of the system.

"We now know our place in the universe," says Ohio State University astronomer Scott Gowdy. "Solar systems like ours are not rare, but we are not the majority, on the other hand."

Gowdy reports the results of the new research at the meeting of the American Astronomical Society in Washington, where he received the Helen B. Award. Werner for astronomy.

The find comes from a project that is a worldwide collaboration whose results are concentrated in the headquarters in the state of Ohio. The project is called the Microlens Tracking Network (MicroFUN), during which the sky is scanned in search of planets outside the solar system.

The project makes use of a method known as gravitational inversion, which occurs when two stars are behind each other, as we see them from our point of view on Earth. The closer star deflects the light coming from the more distant star like a lens. If planets orbit the nearest star, they cause magnification for a short time when they pass near it.

This method is particularly good at detecting giant planets that are outside the solar system - Jupiter-like planets.

MicroFUN's latest research is the product of ten years of work - and one accidental revelation, explains Gowdy and Andrew Gould, professor of astronomy at Ohio University.

Ten years ago, Gaudí calculated in his doctoral thesis the probability of the existence of planets outside the solar system. At the time, he concluded that less than 45% of the stars may form solar systems similar to our own.

Then in December 2009, Gould examined a new planet discovered by the Han Chunju Astronomical Institute, in Korea. Both scientists predicted a variety of features in planets discovered up to that time outside the solar system, and Gould hit on a repeating pattern.

"Basically, I see that the answer was with Scott 10 years ago," says Gold. "With the help of data collected at MicroFUN over the past four years, we can add the robust hypothesis to his calculations, and we can now say how common planetary systems are in our galaxy."

Over the past four years, the MicroFUN survey has discovered only one solar system like ours - a system with two gas giants similar to Jupiter and Saturn.

"We only found this one system, and we should find six more of these by now - if every planet has a system like ours," says Gaudi.

The low amount discovered makes sense only if a small number of planetary systems - about 15% - are similar to ours, the scientists state.
"While it is possible that the initial determination is based on only one solar system and our final number could vary significantly, the study shows that we can begin to make these measurements with the experiments we are doing today," Gowdy says.

As for the possibility of life as we know it elsewhere in the galaxy, scientists will now be able to make rough estimates based on the number of similar planetary systems.

Our solar system may be in the minority, but Gold says the research findings are actually positive.

There are billions of stars out there, even if we narrow the possibilities down to 15% that leaves us with several hundred million systems that might be like ours,” he says.

Press release

29 תגובות

  1. What is the chance of seeing planets not from our galaxy with the existing methods?
    If not, are there any plans to do so?

  2. Mr. A. Dear Ben-Ner (27),

    A. No, you don't see the lens star which is, indeed, the star with the planets. Only the fainter, more distant star is seen.
    B. No, the increase in brightness of the star is not caused by the reflection of light from the face of the planet. The increase in light is caused by the mass of the lensing (closer) star and the mass of its planet deflecting the light of the distant star from its original direction and causing more light rays to reach the viewer (as if they passed through a magnifying glass that focuses the sun's rays).

    Best regards,

  3. To David Polishuk.
    A]. In your first comment (No. 13) you wrote that the lenticular star cannot be seen at all ("...the lenticular star (which cannot be seen at all")). Isn't this a mistake? After all, the lenticular star is the central star around which the orbiting planets move. Isn't it?
    B]. If I understood the method correctly, then in the state of impurity, the reflected light of the planet joins the light of the star and this is how it looks here, a stronger light intensity in the "purified state" compared to the normal intensity of light measured from the star. It is actually a "reverse" of the TRANSIT method
    which measures a decrease in the intensity of the light coming from the star when it is partially "hidden" by the planet.

  4. There is one world!!!!!!!!!!!!!!!!!!

    In the beginning, God created the heavens and the earth!

  5. If now we are going to discover that there are more and more "Earth" planets, then according to human logic at least there is a chance of finding life on these planets. (Thus according to the theory) If this turns out to be true then at least two theories will exist:
    1: that it can be found throughout the universe and this will prove a second theory:
    2: That life can exist according to the time of the universe, meaning also forever.

  6. Ehud Hello,
    Indeed, the method is based on increasing the star's light as a function of time - the time when the lensing star moves between us and the distant, lensing star whose brightness changes. The degree to which the star brightens is a function of the mass of the lensing star. If the lens planet also has a planet, the brightening pattern will not be smooth, but will be accompanied by additional and shorter brightening and weakening phases. The position of these sub-illuminations on the planet's general illumination graph depends on the planet's distance from the lensing star. The intensity of the secondary illuminations depends on the mass of the planet. Several secondary illuminations can indicate several planets of the lensing star (but not necessarily). The orbital speed of the star (or orbital time) is given by Kepler's third law given the mass of the lensing star and the distance of the planet from the star.
    Since the general brightening of the dwarf star takes place over several days, astronomers are watching the event from various locations on Earth to cover the event 24/7 throughout the brightening. It is possible that a secondary brightening due to a planet will be held for a few hours (or less) and the astronomers will miss it. Observations made at Tel Aviv University's Mitzpe Weiz, for example, identified such a secondary clarification that occurred "on our watch". With the years and the events, the group members learned to recognize when the event is significant, sensitive to the planets, and even give fairly accurate predictions of how the enlightenment will end according to its beginning. And everything according to Einstein's theory of general relativity, which is part of the beauty of the whole thing.

  7. rationalize

    Thanks for the fascinating article.

    Thanks to David for the link explaining the measurement method.

    In the context of the measurement method. According to my understanding, the method is based on the change in time of increasing the light from the star
    the remote and therefore does not depend on the details of the lensing star. How do you know that the planets are beyond the "ice line" if the method does not depend on the distance of the planet from the lensing star? Isn't the method limited by the length of the planet's orbit around the lensing star? Is it possible to separate two planets that change the weather at the same time? What are the parameters that can be studied about the planet with this method? I understand that its mass can be estimated, but what about its distance from the lens star? lap speed? Or maybe these details are derived from mass
    The lens star?

  8. Yesterday when I prepared the article it was written that 10% of the universe, and 15% of the galaxy.

    Apparently they changed it in the announcement in Science-Daily.

  9. I don't understand what the big difference is between 10% and 15% when you multiply them by the number of stars in the galaxy and even more so by the number of stars in the universe. Even so, the number of stars is a rough estimate. After all, when they say there are 100 billion stars in the galaxy, no one really counted. 5% difference (which is still an estimate) times 100 billion (roughly) doesn't matter in today's terms

  10. And by the way, I won't be surprised when they find "another Earth"
    And another 10,000 like him (if I'm still alive). This is what it is
    Truly an exciting discovery, but statistically certain.

  11. I don't understand what is surprising about this statement? or in words
    Others, why don't solar systems in the universe resemble each other?
    Or galaxies or supernovae?

    After all, as soon as we defined the concept of a solar system and the way of its formation
    We have already produced a group of billions of similar systems that stand
    In similar criteria……..

    The truth is that what is surprising is why only 10% in the universe and 15% in the galaxy?
    I guess there are many analogies we don't know about yet
    In solar systems but also analog (exceptions) not yet
    Makes systems so completely different from each other.

  12. The article aims to present a summary of observations of the phenomenon of gravitational microlensing. This method uses Einstein's prediction about the deflection of light rays when they pass near a large mass. In certain situations, the deflection of the light rays causes an increase in the brightness of the "refined" star (the star whose light is deflected) by the lensing star (which is not seen at all). The existence of planets around the lensing (front) star will cause different patterns during the brightening of the refinishing star.
    The advantage of this method is its great sensitivity to planets far away from their star and small (even smaller than the Earth!). The other methods for discovering planets (eclipses and the Doppler effect) will not be able to find such planets but rather close and large planets (indeed, about 400 of these are known).
    The fact that a long-term survey was conducted and that in most cases no planets were discovered allows us to estimate a maximum barrier to the existence of planets far from their suns. It should be noted that these are planets that are beyond the "ice line" (in English snowline), which means that water will be frozen there and therefore the chances of life are lower.
    By the way, Tel Aviv University's Wise Observatory is a partner in MicroFun's sky survey, and five researchers from Tel Aviv are also on the list of authors of the article.
    For more details see:

  13. Once again the nonsense of the scientists....I only hope that one day they will discover that life does not have to develop only in solar systems similar to ours, because it is possible that life can develop in forms and conditions that we cannot even imagine..
    So I suggest not to take it too seriously.

  14. Apparently someone had to "balance" all the compliments here (without even checking your IP, I can guess who it is).

    Most of the news I do for Iden are translations, compared to reviews and articles I do for other sites that require in-depth research. Production is a function of time, budget, and need.

  15. Amos Yael does not write any articles. She only translates and doesn't always understand what. Read the source

  16. Hezi,

    Definitely an interesting question. I don't know, but I will check it and get back with an answer.

  17. Amos,

    10% of the universe. 15% of the galaxy. If I have time I will look at the original paper to check how exactly they arrived at this inductive calculation from the galaxy to the universe.

  18. two questions.
    1. The fact that there are several gas giants in the outer part of the system does not require Earth-like planets in the inner part.
    2. Throughout the article 15% is mentioned, why does 10% appear in the title?

    Yael, it's fun to read your articles!

  19. Luke,

    More than 400 planets have been discovered to date, the best method to locate a planet is to use the Doppler effect, if there is a planet then it should have a small gravitational influence on the parent star, you can measure this influence and prove that the planets exist.

  20. There are two more methods for discovering planets (in the order of size of Jupiter) and precisely the method appearing in the article found the fewest planets among the three existing methods.
    If my memory serves me right, several dozens of planets have been discovered to date.

  21. I don't understand the wording "despite this the scientists are optimistic", what does "despite this" mean? 10% sounds like a lot! I think the estimate until today was much lower!

  22. It just statistically increases the chances that there is at least one other Earth similar to ours roaming around somewhere.

  23. Yael,
    Your articles on the subject of the universe are very interesting.

    On this occasion, I would appreciate it if you could clarify a number of ambiguous facts:

    A- Are the observations made with telescopes,
    They are for all directions in the universe, that is: a simple three-dimensional universe, or a "cone" (as suggested by the site manager).

    b- Do the observations relate to Einstein's theories or ignore them.

    C- Is there a significant difference in the density of matter observed in the universe, depending on the direction it is viewed, or is it homogeneous?

    Thank you for factual answers, without "smearing"...

  24. Surely in a few years they will do a new study and a different result will come out than this, so you really can't be sure.
    But I think it is less interesting what percentage of solar systems are similar to ours and more interesting what percentage of planets are around the 'habitable zone' in their system...
    That's what you really need to look for.

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