Two NASA missions are ready for a late-night launch aboard a single rocket. Both aim to unravel mysteries about the universe — one by peering far from Earth, the other by looking closer to home.

The rocket’s chief passenger is SPHEREx, a space telescope that will take images of the entire sky in more than a hundred colors that are invisible to the human eye. Accompanying the telescope is a suite of satellites known collectively as PUNCH, which will study the sun’s outer atmosphere and solar wind.

Here’s what to know about the launch on Saturday night.

When will the missions launch, and how can I watch?

SPHEREx and PUNCH are expected to lift off from the Vandenberg Space Force Base in California no earlier than Saturday, March 8, at 10:09 p.m. Eastern time. The duo is flying on a SpaceX Falcon 9 rocket.

The launch date has been pushed back several times so that mission specialists can ensure the rocket is ready to fly. Should weather or other conditions prevent liftoff from occurring on Saturday, the launch window remains open through April.

NASA is streaming a live broadcast of the launch on its website, beginning at 9:15 p.m. Eastern time on Saturday.

What is SPHEREx?

SPHEREx is short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer. The mouthful of a name is fitting for the vastness of its goal: to survey the entire sky in 102 colors, or wavelengths, of infrared light.

The space telescope, which looks like a giant megaphone, will record around 600 images each day, capturing light from millions of stars in our cosmic backyard and even more galaxies beyond it. Using a technique called spectroscopy, SPHEREx will separate the light into different wavelengths, like a glass prism splitting white light into a rainbow of colors. The color spectrum of an object in space reveals information about its chemical makeup and distance from Earth.

Scientists will use data from SPHEREx to study how the total light emitted by galaxies has changed through cosmic time and to chart where frozen water and other ingredients essential for life exist across the Milky Way. A three-dimensional map of the way galaxies are unevenly clumped across the universe today — some parts thick with galactic gas and dust, others more sparse — will also help researchers deduce the physics behind inflation, the rapid ballooning of the cosmos that occurred a split second after the Big Bang.

What is PUNCH?

Led by the Southwest Research Institute, PUNCH stands for Polarimeter to Unify the Corona and Heliosphere. The mission consists of four satellites, each around the size of a suitcase.

One satellite carries a coronagraph, which will take pictures of the sun’s corona, or outer atmosphere.

The other three are equipped with cameras to capture wider views of solar wind, the hot plasma spewing from the sun’s corona that washes over the solar system.

Each satellite has three polarizing filters, through which only waves of light aligned in a particular direction can pass. That’s similar to the way polarized sunglasses block glare. By measuring polarized light, scientists can reconstruct the three-dimensional position, speed and direction of the solar wind as it streams away from the sun.

These measurements will help solar physicists understand the boundary where the sun ends and the solar wind begins. The satellites will also observe coronal mass ejections, violent blasts of solar material, as they evolve on their way to Earth. This data will help forecasters better predict the potential effects of space weather, from power outages to glittering northern lights.

Where are SPHEREx and PUNCH going?

Both missions will orbit approximately 400 miles above Earth’s terminator, the line separating day and night on our planet, circling over the north and south poles. This type of orbit is known as sun-synchronous because it keeps the spacecraft oriented in the same position relative to our sun.

That’s advantageous for PUNCH, as it allows the constellation of satellites to keep a clear view around the sun at any point along its orbit. It also allows SPHEREx to stay pointed away from the sun, avoiding infrared light from our home star that could mask fainter signals from faraway stars and galaxies.