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What are some skywatching highlights in April 2023? Mercury reaches its highest in the evening sky for the year for Northern Hemisphere observers. The Moon makes its monthly rounds to pair up beautifully with several planets. And viewing conditions may be ideal for the annual Lyrid meteor shower, thanks to no interference from the Moon. Additional information about topics covered in this episode of What's Up, along with still images from the video, and the video transcript, are available at https://solarsystem.nasa.gov/skywatching/home.

Venus, our planetary neighbor, is a hot, hellish unforgiving world and NASA has selected two bold new missions to study this inferno-like planet: DAVINCI+ and VERITAS. Are Venus and Earth fundamentally unique worlds? Or are the differences between these ‘twins’ only cosmetic? Answering this question is key to understanding what makes other rocky planets habitable and, ultimately, emerge with life.

Watching a particularly beautiful movie of the sun helps show how the lines between science and art can sometimes blur. But there is more to the connection between the two disciplines: science and art techniques are often quite similar, indeed one may inform the other or be improved based on lessons from the other arena. One such case is a technique known as a "gradient filter" — recognizable to many people as an option available on a photo-editing program. Gradients are, in fact, a mathematical description that highlights the places of greatest physical change in space. A gradient filter, in turn, enhances places of contrast, making them all the more obviously different, a useful tool when adjusting photos. Scientists, too, use gradient filters to enhance contrast, using them to accentuate fine structures that might otherwise be lost in the background noise. On the sun, for example, scientists wish to study a phenomenon known as coronal loops, which are giant arcs of solar material constrained to travel along that particular path by the magnetic fields in the sun's atmosphere. Observations of the loops, which can be more or less tangled and complex during different phases of the sun's 11-year activity cycle, can help researchers understand what's happening with the sun's complex magnetic fields, fields that can also power great eruptions on the sun such as solar flares or coronal mass ejections. The images here show an unfiltered image from the sun next to one that has been processed using a gradient filter. Note how the coronal loops are sharp and defined, making them all the more easy to study. On the other hand, gradients also make great art. Watch the movie to see how the sharp loops on the sun next to the more fuzzy areas in the lower solar atmosphere provide a dazzling show.