Solar System


Help Complete the Solar System!

Be a crucial part of the creation of the markers for Mercury, Venus, Mars, and Pluto. We're also embarking on the mission to establish multiple markers within each planet's orbit. So, whether you're eager to volunteer your time, resources, or contribute funding, please visit our Donate and Volunteer pages.

*These are satellite photos sourced from NASA's Flickr Commons and are used for educational and informational purposes.


  • Venus is in Earth's sky bright enough to be visible without aid, making it one of the star-like classical planets that human cultures have known and identified throughout history, particularly for being the third brightest object in Earth's sky after the Sun and the Moon.

  • Some cultures did not recognize Venus as a single entity. They previously assumed it to be two separate stars on each horizon: the morning and evening star.

  • In the Old Babylonian period, the planet Venus was known as Ninsi'anna, and later as Dilbat The name "Ninsi'anna" translates to "divine lady, illumination of heaven", which refers to Venus as the brightest visible "star".

When the Italian physicist Galileo Galilei first observed the planet with a telescope in the early 17th century, he found it showed phases like the Moon, varying from crescent to gibbous to full and vice versa. When Venus is furthest from the Sun in the sky, it shows a half-lit phase, and when it is closest to the Sun in the sky, it shows as a crescent or full phase. This could be possible only if Venus orbited the Sun, and this was among the first observations to clearly contradict the Ptolemaic geocentric model that the Solar System was concentric and centered on Earth. This led to the 1639 transit of Venus being accurately predicted by Jeremiah Horrocks and observed by him and his friend, William Crabtree, at each of their respective homes.


  • While Venus is relatively nearby, its extreme temperatures and crushing atmosphere make landing incredibly difficult.

  • The longest any probe has lasted on the surface is just a few hours.

  • Over 40 missions have launched to Venus, either as destinations or as fly-bys for other destinations.

Most of these have come from the former Soviet Union or the USA, but recent missions from ESA and Jaxa have helped open up the mysteries of this stormy neighbor. Most of what we learned early on came from NASA’s Mariner missions and the USSR’s Venera missions. A variety of fly-by, orbital, and impact missions met with varying degrees of success, but all provided crucial information to help move humanity forward into space. Magellan and Venus Express have been perhaps the most successful so far helping us map the surface and better understand the atmosphere of Venus. Venus has also been the target for the first use of a solar sail (Ikaros) as well as atmospheric flight on another planet.


  • It's a cloud-swaddled planet named for a love goddess, often called Earth’s twin.

  • Our nearest planetary neighbor, the second planet from the Sun, has a surface hot enough to melt lead.

  • The atmosphere is so thick that, from the surface, the Sun is just a smear of light.

In some ways it is more an opposite of Earth than a twin: Venus spins backward, has a day longer than its year, and lacks any semblance of seasons. It might once have been a habitable ocean world, like Earth, but that was at least a billion years ago. A runaway greenhouse effect turned all surface water into vapor, which then leaked slowly into space. The present-day surface of volcanic rock is blasted by high temperatures and pressures. Asked if the surface of Venus is likely to be life-bearing today, we can give a quick answer: a hard “no.”

Last updated August 18, 2023. Content written by Trevor Macduff.