Earth's twin in size and mass, and in nothing else at all. Where it is right now, how big and how heavy, and what is still unexplained.
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Distances from the sun are in AU — one AU is the Earth’s average distance, 149,597,870 km — and the angle is where the body sits around its orbit, measured from the March equinox direction.
The mass is worked out from Venus’s gravitational parameter and the gravity from that and its radius; the year comes from Kepler’s third law and the width is the same figure the simulator draws with. None of them is typed in beside the picture, so none of them can disagree with it.
Both planets are moving, so the gap between them swings enormously — and the closest approaches are not all equal, because the orbits are ellipses rather than circles. These are the next four, solved from the orbits rather than looked up.
Click a date to take the simulator there. These are minimum-distance moments, which fall near — but not exactly on — opposition.
Every one of these is genuinely unsettled — not simplified for the page, not waiting on a textbook update.
Either a giant impact flipped it, or the thick atmosphere did it: solar tides in an atmosphere that heavy, working against friction between core and mantle, can in principle turn a planet over and stall its spin without hitting it. The two histories are hard to tell apart from the outside, and the answer decides whether Venus was violently rearranged or just slowly wound down.
Its deuterium-to-hydrogen ratio is about 150 times Earth's, which is the signature of a planet that has lost an enormous amount of ordinary water to space. How much, and when the last of it went — early, or as recently as a billion years ago — is unresolved, and the answer changes whether Venus was ever habitable.
A 2020 claim of phosphine in the cloud deck, where the temperature is mild even though the surface is not, has been argued about ever since; later observations have both supported and failed to reproduce it, and there is no accepted abiotic or biological explanation. Treat it as an open measurement question, not as a discovery.
Findings reviewed August 2026. Space science moves; a date on a finding is part of the finding.
Inward: Mercury. Outward: Earth. Or go back to the whole system, where every planet is on screen at once.
The date, the zoom, the span, the speed, the layers and any flight path are all in the address bar, so copying the URL shares exactly what is on screen. Set it up above, then take the link — it is the quickest way to hand a class one specific thing to look at.
This one is about the whole system. If the question is where the sun and the moon are from where you are standing — what time the sun comes up, why tonight's moon is the shape it is — that is the Sun, Earth & Moon movement simulator, which has a page for every city and a slider over a day, a week or a month.
Also: the classroom guide · sunrise & sunset by city · moon phase & moonrise · lunar eclipses · how the positions are worked out
Why does it spin backwards, and so slowly? Either a giant impact flipped it, or the thick atmosphere did it: solar tides in an atmosphere that heavy, working against friction between core and mantle, can in principle turn a planet over and stall its spin without hitting it. The two histories are hard to tell apart from the outside, and the answer decides whether Venus was violently rearranged or just slowly wound down.
Did Venus ever have oceans? Its deuterium-to-hydrogen ratio is about 150 times Earth's, which is the signature of a planet that has lost an enormous amount of ordinary water to space. How much, and when the last of it went — early, or as recently as a billion years ago — is unresolved, and the answer changes whether Venus was ever habitable.
Is anything happening in the clouds? A 2020 claim of phosphine in the cloud deck, where the temperature is mild even though the surface is not, has been argued about ever since; later observations have both supported and failed to reproduce it, and there is no accepted abiotic or biological explanation. Treat it as an open measurement question, not as a discovery.