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  2. Astronomical filter - Wikipedia

    en.wikipedia.org/wiki/Astronomical_filter

    These H-alpha filters are much narrower than those use for night H-alpha observing (see Nebular filters below), passing only 0.05 nm (0.5 angstrom) for one common model, [5] compared with 3 nm-12 nm or more for night filters. Due to the narrow bandpass and temperature shifts often telescopes like that are tunable within about a ±0.05 nm.

  3. Barnard 68 - Wikipedia

    en.wikipedia.org/wiki/Barnard_68

    Having a dark cloud in the solar neighborhood greatly facilitates observation and measurement. If not disrupted by external forces, the stability of dust clouds is a fine balance between outward pressure caused by the heat or pressure of the cloud's contents, and inward gravitational forces generated by the same particles (see Jeans instability ...

  4. Chord (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Chord_(astronomy)

    Transit of mercury chord across the sun. In the field of astronomy the term chord typically refers to a line crossing an object which is traversed during an occultation event. . By taking accurate measurements of the start and end times of the event, in conjunction with the known location of the observer and the object's orbit, the length of the chord can be determined giving an indication of ...

  5. Don't have eclipse glasses? How to view the eclipse safely ...

    www.aol.com/news/see-solar-eclipse-safely-doctor...

    Stand with your back to the sun so you can see the shadow of your head and shoulders. Put the other piece of paper on the ground and hold the piece with the aluminum foil above it.

  6. Diffuse sky radiation - Wikipedia

    en.wikipedia.org/wiki/Diffuse_sky_radiation

    The blue sky spectrum contains light at all visible wavelengths with a broad maximum around 450–485 nm, the wavelengths of the color blue. Diffuse sky radiation is solar radiation reaching the Earth 's surface after having been scattered from the direct solar beam by molecules or particulates in the atmosphere .

  7. Cheap and deadly: Why vehicle terror attacks like the Bourbon ...

    www.aol.com/cheap-deadly-why-vehicle-terror...

    Experts say vehicle-based attacks are simple for a 'lone wolf' terrorist to plan and execute, and challenging for authorities to prevent.

  8. Lawsuit accuses major food companies of marketing 'addictive ...

    www.aol.com/news/lawsuit-accuses-major-food...

    By Brendan Pierson (Reuters) -Major food companies, including Kraft Heinz, Mondelez and Coca-Cola, were hit with a new lawsuit in the U.S. on Tuesday accusing them of designing and marketing ...

  9. Blue hour - Wikipedia

    en.wikipedia.org/wiki/Blue_hour

    Blue hour at the Old Cathedral of the Holy Name of Jesus, Bragança in Portugal. The blue hour (from French l'heure bleue; [1] [a] pronounced [lœʁ blø]) is the period of twilight (in the morning or evening, around the nautical stage) when the Sun is at a significant depth below the horizon. During this time, the remaining sunlight takes on a ...