Erwin Müller Blog

Planetary Systems Compared with Our Solar System

There are over 2000 confirmed discovered exoplanets, that is, planets that orbit other star systems than ours. I was researching the exoplanetary systems that are available in the various open catalogs, like the listed below.

The article compares the semi-major axis of the discovered planets with the orbits of our solar system planets. Depicted are the orbits of the solar system planets, their names, masses and radii are noted in the legend bottom left, and the semi-major axis of the discovered planets, their names, masses and radii (if known) are noted in the upper right corner. To help identifying the systems, the smaller system have a gray circle as background. All of the graphs have the same scale, from -70 to 70 AU.

Gliese 667 C

Gliese 667 [openexoplanetcatalogue.com]


“The planetary system Gliese 667 hosts at least 7 planets. Note that the system is a multiple star system. It hosts at least 3 stellar components.”


The star Gliese 667 C is about 22 ly away. All the planets listed are closer to the host star than the Earth. The method of discovery was the radial-velocity method, that explains why only the closest planets are discovered. The system Gliese 667 have probably more planets in a more Jupiter like orbits.

Sol Gliese 667 C

Sol Gliese 667 C

HD 10180

HD 10180 [openexoplanetcatalogue.com]


“The planetary system HD 10180 hosts at least 9 planets. […] The age of the star is 7.3 Gigayears.”


The star HD 10180 is about 128 ly away. All the planets listed are closer to the host star than Jupiter. The method of discovery was the radial-velocity method, that explains why only the closest planets are discovered. The system HD 10180 have probably more outer planets.

Sol HD 10180

Sol HD 10180

Kepler-90

Kepler-90 [openexoplanetcatalogue.com]


“The planetary system Kepler-90 hosts at least 7 planets.”


The star Kepler-90 is about 2,722 ly away. All the planets listed are closer to the host star than Mars. The method of discovery was the transit photometry method. The system Kepler-90 have probably more outer planets, but the transit period is too long for us to observe (Jupiter have an orbital period of about 12 years and Saturn an orbital period of about 29 years).

Sol Kepler-90

Sol Kepler-90

HR 8799

HR 8799 [openexoplanetcatalogue.com]


“The planetary system HR 8799 hosts at least 4 planets.”


The star HR 8799 is about 39 ly away. The method of discovery was the direct imaging method. Probably we can only see the outer planets because of the method used. Smaller planets would be not visible due to the light of the star. In the graphic the gray background circle indicates the orbit of Neptune, because HR 8799 b’s semi-major axis is 68 AU, way outside of the orbit of Neptune.

Sol HR 8799

Sol HR 8799

47 Uma

47 Uma [openexoplanetcatalogue.com]


“The planetary system 47 Uma hosts at least 3 planets.”


The star 47 Uma is about 46 ly away. The method of discovery was the radial-velocity method. Probably we can only see the outer planets because of the method used. The discovered planets of 47 Uma have Jupter-like masses and thus have a detectable wobble effect on the star. Lighter inner planets would not have a strong wobble effect.

Sol 47 Uma

Sol 47 Uma

HU Aqr

HU Aqr [openexoplanetcatalogue.com]


“The planetary system HU Aqr hosts at least 3 planets. Note that the system is a multiple star system. It hosts at least 2 stellar components.”


The method of discovery was the transit-timing variation method.

Sol HU Aqr

Sol HU Aqr

55 Cancri

55 Cancri [openexoplanetcatalogue.com]


“The planetary system 55 Cancri hosts at least 5 planets. Note that the system is a multiple star system. It hosts at least 2 stellar components.”


The star 55 Cancri is about 40 ly away. The method of discovery for the planets b, c, d and f was the radial-velocity method and the planet 55 Cnc e was discovered via the transit-timing variation method.

Sol 55 Cancri

Sol 55 Cancri

Upsilon Andromedae

Upsilon Andromedae [openexoplanetcatalogue.com]


“The planetary system Upsilon Andromedae hosts at least 4 planets. Note that the system is a multiple star system. It hosts at least 2 stellar components.”


The star Upsilon Andromedae is about 44 ly away. The method of discovery for the planets was the radial-velocity method.

Sol Upsilon Andromedae

Sol Upsilon Andromedae

HD 141399

HD 141399 [openexoplanetcatalogue.com]


“The planetary system HD 141399 hosts at least 4 planets.”


The star HD 141399 is about 118 ly away. The method of discovery for the planets was the radial-velocity method.

Sol HD 141399

Sol HD 141399

Solar System

The graphic bellow shows our solar system, based on the data of the aphelion and perihelion in AU, and the radii of the planets scaled to the radii of Jupiter.

Solar System

Solar System

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