Artemis II and its four-person crew have entered the Moon’s “sphere of influence,” meaning the spacecraft is more affected by lunar gravity than the Earth’s pull. The transition occurred at a distance of 39,000 miles from the Moon, four days, six hours and two minutes into the mission. The next and most important phase will happen tomorrow when the craft loops around the Moon’s far side, taking humans deeper into space than they’ve ever been before.

At their apogee, Astronauts Reid Wiseman, Christina Koch, Victor Glover and Canada’s Jeremy Hansen will be 252,757 miles from Earth. That will break the previous record held by the Apollo 13 crew by just over 4,000 miles. They’re the first humans to cross the lunar threshold since 1972’s Apollo 17 moon landing mission.

The crew spent this weekend carrying out preparations for their lunar flyby. That included manual piloting demonstrations, reviewing their science objectives for the six-hour observation period and evaluating their space suits, which are there for life support in the event of an emergency and for their return home. But, they've had plenty of time to take in the views, too — and those views sure are spectacular. In the latest series of images shared by the space agency, the astronauts are seen gazing at Earth through the windows of the Orion spacecraft. 

Orion will reach the moon's vicinity shortly after midnight on Monday, April 6. Later that day, the crew is expected to reach a point farther than any humans have traveled from Earth, surpassing the record of 248,655 miles from Earth set by the Apollo 13 astronauts in 1970. 

NASA

The lunar observation period will start at 2:45PM ET, and a few hours later, they'll be behind the moon and briefly drop out of communication. The spacecraft's closest approach to the moon is expected to occur at 7:02PM, when it will be 4,066 miles from the surface. "From that distance, the crew will see the entire disk of the Moon at once, including regions near the north and south poles," according to NASA. The crew will later get a chance to see a solar eclipse "as Orion, the Moon, and the Sun align in such a way that the astronauts will see our star disappear behind the Moon for about an hour." NASA will have coverage of the flyby starting at 1PM ET.

Update April 7 at 1:40 AM ET: The post has been updated with news that Artemis II has entered the Moon’s sphere of influence.

We got to share in a rare moment of collective awe this week as four astronauts blasted off toward the moon, beginning a 10-day journey that will take them farther from Earth than any humans have traveled in the last 50 years. It'll still be a little while before they reach their destination — the Orion spacecraft is expected to loop around the moon on Monday — but they've already seen some pretty incredible stuff on the way there. Here's the latest on the Artemis II mission, and other interesting science stories from this week. 

Artemis II crosses the halfway point

After years of planning, NASA astronauts Reid Wiseman, Victor Glover and Christina Koch, along with Canadian Space Agency (CSA) astronaut Jeremy Hansen, are finally on their way to the moon for the Artemis II mission. This test flight is a crucial step in NASA's plans to send humans to the surface of the moon again for the first time since Apollo 17, and the high-stakes launch went off without a hitch on Wednesday. 

The Artemis II crew is now more than halfway to the moon, according to NASA. When Orion reaches the moon on April 6, the astronauts will have a six-hour window of opportunity to observe the partially lit lunar far side, which can't be seen from Earth. If you're curious about where exactly the astronauts are at any given moment, you can track the mission by visiting NASA's Artemis Real-Time Orbit website. And, if you just want to see what space looks like from Orion, here's a livestream from outside the capsule. The moon is now in view!

The crew did experience some technical difficulties after leaving the ground, though all were resolved fairly quickly. Early Thursday morning, Wiseman contacted mission control to troubleshoot some issues with a Surface Pro he was attempting to use, noting, "I have two Microsoft Outlooks and neither one of those are working." Relatable. The Artemis II crew was also greeted by a malfunctioning toilet not long into the flight, and astronaut Koch had to work with the ground team to figure out a fix — which they thankfully were able to do. In a livestream later, the astronaut joked that she is now a space plumber. 

Small issues aside, the Artemis II mission is off to a pretty amazing start. The Orion spacecraft completed its translunar injection burn on Thursday, officially taking it out of Earth orbit and putting it on its way to the moon. Commander Wiseman shared some pictures of the view from Orion's windows afterward, and they are breathtaking. In one unbelievably crisp shot of Earth, you can even see two auroras. And there's plenty more observations to come. 

Students discover a nearly pristine ancient star

Using data from the Sloan Digital Sky Survey (SDSS), a group of undergraduate students at the University of Chicago has discovered what's thought to be one of the oldest stars ever observed. Their analysis indicates that the star, called SDSSJ0715-7334, was born in the nearby Large Magellanic Cloud billions of years ago before eventually making its way to the Milky Way.

Vedant Chandra and the SDSS collaboration Background ESA/Gaia image, A. Moitinho, A. F. Silva, M. Barros, C. Barata, University of Lisbon; H. Savietto, Fork Research

The star was one of 77 that the students selected for closer observation after poring through the SDSS data in their "Field Course in Astrophysics” class, which is led by Professor Alex Ji, the deputy Project Scientist for SDSS-V. SDSS-V is an ongoing all-sky survey that's mapping the Milky Way. After creating their list, they set out to observe the stars during a field trip to Carnegie Science’s Las Campanas Observatory in Chile, and honed in on SDSSJ0715-7334 on day two. The team found it's made mostly of hydrogen and helium, with very little carbon and iron. In the paper published in the journal Nature Astronomy, the researchers note that this composition could be the product of a primordial supernova.

"This ancient immigrant gives us an unprecedented look at conditions in the early universe,” said Ji in a statement. Ji added, “The star has so little carbon that it suggests an early sprinkling of cosmic dust is responsible for making it. This formation pathway has only been seen once before.”

Before you go, be sure to check these stories out too:

• What’s going on with Donut Lab's so-called super battery?

• SpaceX has reportedly filed for the biggest IPO in history

The first crewed mission of NASA's Artemis moon program may take off in a matter of days, with a launch window that opens on April 1, and as preparations are underway for that, the space agency is refocusing its plan to establish a human presence on the moon. NASA announced major changes to its approach for moon landings that are expected to play out over the coming years, including axing its plan to build an orbiting station called Gateway. Read on to learn more about the agency’s new vision for the moon, along with other interesting science stories from this week. 

Gateway out, moon base in

Just a few weeks after overhauling its Artemis program, NASA this week announced even more changes to its plans for putting astronauts back on the moon. Most notably, the space agency is abandoning the lunar Gateway project, which was intended to be the first ever space station orbiting the moon. Gateway, an international collaboration, wasn't just going to support exploration of the lunar surface, but deep space missions too. But the writing has been on the wall for some time; in the Trump administration's proposed budget cuts last May, Gateway was among the programs selected for the chopping block. Now, NASA is officially putting it on "pause" and plans to build a $20 billion moon base instead. 

“NASA is committed to achieving the near‑impossible once again, to return to the moon before the end of President Trump’s term, build a moon base, establish an enduring presence, and do the other things needed to ensure American leadership in space," NASA Administrator Jared Isaacman said at the agency's Ignition event on Tuesday. 

There are three phases to the moon base plan, according to NASA: first using contractors to send rovers and instruments to the moon through the Commercial Lunar Payload Services (CLPS) program; next establishing "semi-habitable infrastructure," with astronauts on the ground and collaboration with other space agencies; and finally adding "heavier infrastructure" to support long-term stays on the lunar surface, including the Italian Space Agency's Multi-purpose Habitats and the Canadian Space Agency's Lunar Utility Vehicle. NASA says it's aiming to start this plan off with crewed moon landings every six months following the Artemis V mission, which is currently planned for 2028.

Comet 41P pulls a reverse card

A study published this week in The Astronomical Journal describes what's said to be the first observation of a comet reversing its spin. Observations taken several months apart in 2017 show the comet 41P/Tuttle-Giacobini-Kresák starting to spin more slowly after making a close flyby of the sun, before picking up speed again by December of that year. Its spin period, measured using NASA’s Neil Gehrels Swift Observatory, was about 46-60 hours in May 2017, but later observations by the Hubble Space Telescope showed it was just 14 hours, according to NASA. The researchers say what likely happened is that the heat from the sun caused the comet's ice to sublimate, sending gases spewing off its sides.

“Jets of gas streaming off the surface can act like small thrusters,” author David Jewitt of the University of California at Los Angeles, said in a statement. “If those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.” Jewitt compares it to pushing a merry-go-round. “If it’s turning in one direction, and then you push against that, you can slow it and reverse it.”

Comet 41P is thought to have come from the Kuiper Belt and passes through the inner solar system every 5.4 years. It's small, with a nucleus of just around .6 miles, and the researchers found it's become less active over recent years, indicating that there are changes taking place on the surface. While it's thought to have been in this orbit for about 1,500 years, it now appears to be rapidly evolving, and the rotational changes — which could cause structural instability if it continues — could mark the beginning of the end for it. “I expect this nucleus will very quickly self-destruct,” said Jewitt.

Saturn in a new light

NASA/ESA/CSA

Stunning images of Saturn released this week by NASA, ESA and CSA provide a more detailed look at the many layers of the ringed planet's "busy" atmosphere. The images, which show storms, clouds at different depths, Saturn's "ribbon wave" jet stream and so much more were taken by the Hubble Space Telescope and the James Webb Space Telescope in 2024. Read more about it here.