The DownlinkDec 29, 2023

Happy Perihelion!

Space Snapshot

Cluster in the cloud

This image from the Hubble Space Telescope captures the essence of year-end celebrations: lighting sparklers, popping champagne, and setting off fireworks. This year, there’s plenty to celebrate.

Together, we accomplished so much in 2023. With your help, we can launch into 2024 with even more momentum. Make a gift now to keep great missions going and your donation will be matched for an even greater impact! Don't miss your chance to be part of the future of space. Thank you, and happy New Year!

Pictured: The densely packed globular cluster known as NGC 2210, which is situated in the Large Magellanic Cloud about 157,000 light-years from Earth. Image credit: ESA/Hubble/NASA/A. Sarajedini.

Fact Worth Sharing

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Earth’s perihelion happens close to the New Year every year. Earth's orbit around the Sun isn't perfectly circular, so we get closer to and farther from the Sun depending on where we are in that orbit. In 2024, perihelion — our closest point to the Sun — will be on Jan. 2-3.

Mission Briefings

Jupiter juno cloud altitudes

An exoplanet hunter has been used to study Jupiter. Researchers recently used the ESPRESSO spectrograph on the European Southern Observatory’s Very Large Telescope to measure wind speeds on Jupiter. Once the technique has been mastered for Jupiter, the team hopes to apply it to the atmospheres of other gaseous planets within our Solar System, with Saturn as the next target. Pictured: An image from the Juno spacecraft that has been processed to highlight different cloud altitudes on the gas giant. Image credit: NASA/JPL-Caltech/SwRI/MSSS/Image processing by Thomas Thomopoulos.


Japan’s SLIM spacecraft has successfully entered lunar orbit. The Japan Aerospace Exploration Agency’s (JAXA) Smart Lander for Investigating Moon (SLIM) is now gearing up to make a precision landing on the Moon. A successful landing would make Japan the fifth country to land on the Moon, and would prove a new method of highly accurate landings that could boost the scientific value of future missions.

From The Planetary Society

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It’s been a big year here at The Planetary Society. To recap the highlights, listen to this week’s Planetary Radio for interviews with several members of our team as we revisit some of 2023's groundbreaking discoveries, Society achievements, and favorite space exploration moments. Pictured: A highlight of the year was the Lucy spacecraft’s discovery of a pair of tiny asteroid moonlets orbiting a larger asteroid. Image credit: NASA/Goddard/SwRI/Johns Hopkins APL.

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Is one of your New Year’s resolutions to read more? If so, be sure to join The Planetary Society’s book club. We meet virtually every month to discuss a new space-related book with the author or a related expert. This month’s book is "A City on Mars" by Kelly and Zach Weinersmith, which explores what it would really take to settle on another world. The authors will join host Mat Kaplan for a live Q&A on Jan. 4. It all happens in our members-only digital community. If you aren’t already a member, join today!

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The Galilean moons were discovered almost exactly 414 years ago. The Italian astronomer Galileo Galilei first observed these four moons through a telescope in early January 1610, forever changing our understanding of the Cosmos. Io, Europa, Ganymede, and Callisto, collectively known as the Galilean moons, are Jupiter’s four largest moons, and were the first moons other than Earth’s to be discovered. Learn more about why that made such a big impact, and what we know about these fascinating worlds.

What's Up

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The Quadrantid meteor shower peaks this week overnight between Jan. 3 and 4. While you’re out meteor-watching, look for Jupiter high in the east, with Saturn shining below it. Early risers will see Venus shining super-bright in the predawn east, low to the horizon. Learn more at

Wow of the Week

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For many Earthlings, this time of year is busy and sometimes stressful. Amidst the hubbub of the holidays, it’s nice to zoom out and reflect on our place in the vastness of the Cosmos. This image might help. NASA astronaut Scott Kelly captured this view from the International Space Station, showing Jupiter, Venus, and the Moon shining beyond Earth’s limb. Image credit: NASA Goddard Space Flight Center/S. Kelly.

Send us your artwork!

We love to feature space artwork in the Downlink. If you create any kind of space-related art, we invite you to send it to us by replying to any Downlink email or writing to [email protected]. Please let us know in your email if you’re a Planetary Society member!