Terraforming 

Microbes that can survive in extremely high temperature and acidic conditions are genetically engineered to transport them into the atmosphere of Venus, using carbon dioxide and light as energy sources. These microbes slowly consume carbon dioxide in the process of survival and reproduction.

British scientist Paul Birch proposed bombarding Venus' atmosphere with hydrogen. The resulting reaction would produce graphite and water, the latter of which would fall to the surface and cover roughly 80% of the surface in oceans. Given the amount of hydrogen needed, it would have to be got directly from one of the gas giants or many asteroids.

The concept of solar shades has been discussed, in which a group of small spaceships blocks the sunlight hitting the surface of the planet, or a giant mirror directly reflects the sunlight back into space, so as to achieve the effect of reducing the surface temperature. 

Another alternative is the solar mirror, which can be set up in the atmosphere or on the surface of Venus. The mirrors can consist of large arrays of light-reflecting balloons, as well as carbon nanotubes or graphene sheets. The former solution has two advantages: First, atmospheric mirrors can be fabricated on the planet using the rich carbon resources native to Venus. Second, Venus' atmosphere is dense enough that large structures like mirrors can easily float above the clouds.

If you do not change the rotation of Venus, you can change the frequency of light. A set of orbital sunglasses is set up between Venus and the sun. Combined with solar mirrors in polar orbits, a 24-hour light cycle can be created on the surface of Venus.

Or we can also start from accelerating the rotation speed of Venus, such as using celestial bodies to collide with the surface of Venus or fly close by celestial bodies with a diameter greater than 96.5 kilometers. It has also been proposed to use a mass accelerator or dynamic compression device (a device envisaged by the study that uses a magnetic field to accelerate mass flow) to generate the forces needed to speed up Venus' rotation, eventually making its day-night cycle the same as Earth's.

The Martian polar cap is a reservoir of carbon dioxide and water on Mars and is several kilometers thick. If the carbon dioxide, which has been frozen into dry ice, can be melted and released into the atmosphere, the Martian atmosphere can be made a little denser. At the same time, we're lucky because this carbon dioxide happens to be a greenhouse gas (and so is water vapor), so its entry into the atmosphere could add to Mars' plans to warm it up.

First, build a super mirror with a large diameter (more than 100 kilometers), put it in an orbit above Mars, and rely on reflected sunlight to heat up Mars. Second, search for asteroids containing ammonia to hit Mars in space, releasing ammonia, a greenhouse gas, to heat up Mars. Or directly bomb Mars with a nuclear bomb to heat up the planet rapidly. Third, and what humans are best at, building various chemical factories on Mars and constantly releasing greenhouse gases. According to scientists’ calculations, using this method, the temperature of Mars can be increased by 28 degrees within 30 years.

The atmosphere of Mars is so thin and its density is only 1% of that of Earth's. Under such low pressure, liquid water would not exist on the surface of Mars. Scientists have found liquid water beneath the Martian poles, but not on the surface. Mars itself will also release some gas as its temperature rises. The carbon dioxide stored in the soil is released, which increases the Martian pressure step by step. The ice buried in the soil also melts and evaporates into water vapor, which can lead to some rain and snow.

When the Martian atmospheric pressure reaches 20% of the Earth's atmospheric pressure, the average temperature in the equatorial region of Mars will remain above zero, lakes and rivers will form there, and humans can grow suitable plants to generate oxygen. There is no shortage of carbon dioxide on Mars, the gas that plants use for photosynthesis. Another point is that there are many minerals on Mars, such as iron oxide, and people can use abundant minerals to make enough oxygen.

If an asteroid with a diameter of more than 100 kilometers hits Mars at a suitable speed and angle, the lava inside Mars can be activated, and the magnetic field of Mars will also be established. However, the scale of such an impact is too large. At present, human technology cannot do it at all, and if Mars is hit by such an impact, the situation of the entire planet will be greatly changed.

In addition, some scientists have imagined placing a huge magnetic satellite near Mars. The magnetic satellite is located at the L1 Lagrangian point between Mars and the sun, and the magnetic field generated by it is used to shield it. The impact of the solar wind on the Martian atmosphere. This method is relatively easy, but it is still not achievable by today's human technology, because the magnetic field produced by this magnetic field generator has a diameter of 10,000-30,000 kilometers, and the largest magnetic field produced by humans is not even one kilometer in diameter.