1️⃣ NASA Announces Artemis II Launch Date
NASA is targeting no earlier than April 1 for the launch of Artemis II, the first crewed mission under the Artemis program. Astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen will fly an approximately 10-day journey around the Moon aboard the Orion spacecraft. The mission will test Orion's life support systems with crew on board for the first time.
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2️⃣ XRISM Telescope Measures the Hot Wind of Galaxy M82
Using the high-resolution XRISM telescope, scientists have made the first direct measurement of the temperature and velocity of hot gas in the starburst core of galaxy M82. The hot gas reaches 23 million Kelvin and has a mass of roughly 600,000 solar masses, with velocities consistent with a freely expanding wind exceeding the galaxy's escape velocity. The findings confirm that thermal pressure alone is sufficient to drive a multiphase galactic wind.
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3️⃣ Superluminous Supernovae: A Magnetar Behind the Record Brightness
Superluminous supernovae shine 10 to 100 times brighter than ordinary stellar explosions, but their energy source has remained uncertain. A new study models a newly born millisecond magnetar as the power source and finds that for the nearest known SLSN — SN 2017egm — the predicted high-energy gamma rays match a recent Fermi LAT detection. The model also generates testable predictions for neutrino and electromagnetic signatures.
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4️⃣ GravNet: A Global Network to Hunt High-Frequency Gravitational Waves
Researchers have proposed GravNet, a conceptual global detector network designed to search for gravitational waves in the MHz to GHz frequency range — a window invisible to current detectors like LIGO. Sources at these frequencies may be connected to fundamental open questions in cosmology. The approach relies on synchronized measurements across geographically separated detectors, with signal correlations used to distinguish real events from noise.
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5️⃣ April 2026 Skywatching Highlights
On April 3, Mercury reaches its greatest elongation — the best opportunity to spot the planet this year, low in the eastern sky before sunrise. The Lyrid meteor shower, fed by debris from Comet Thatcher, peaks overnight on April 21–22 near the bright star Vega. On April 27, Comet C/2025 R3 makes its closest approach to Earth at 71 million kilometers and should be visible through binoculars or a small telescope in the constellations Pegasus and Pisces.
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