Baryon acoustic oscillations, an Uncommon card

The card carries these facts from its Wikipedia article.

• In the same way that supernovae provide a "standard candle" for astronomical observations, BAO matter clustering provides a "standard ruler" for length scale in cosmology.
• The length of this standard ruler is given by the maximum distance the acoustic waves could travel in the primordial plasma before the plasma cooled to the point where it became neutral atoms, which stopped the expansion of the plasma density waves, "freezing" them into place.
• The length of this standard ruler can be measured by looking at the large scale structure of matter using astronomical surveys.

Rarity in WikiCards follows a year of Wikipedia page views: the most read articles become Epic and Legendary cards. The Baryon acoustic oscillations article was read about 50,000 times in a year. ATK comes from the length of the article and DEF from its quality, so this card hits with 68 and blocks with 58: each hit it takes is cut by 23 %.

Open packs. Each pack holds five cards drawn from real Wikipedia articles, the rarest last, and the fifth card is always Rare or better. The odds are shown in the game. A free pack arrives every hour and two can wait, and the Coins you win in duels buy more packs.

The cards just above and just below Baryon acoustic oscillations in the power ranking, all domains together.