The space snowman at the edge of our solar system is actually

first_imgBecause the two lobes aren’t spheres, their height, width, and depth can be seen as three distinct axes, and all three axes of the lobes are nearly perfectly aligned, as if they had been laid end-on-end like dominos. This type of alignment would be expected if the duo formerly orbited each other in close proximity, their gravity gently tugging back and forth. “It’s very improbable this would arise completely by chance,” McKinnon says.The new images support a newer theory of planetary formation, called the streaming instability, as Science reported in January. Fifteen years ago, scientists proposed that boulder-size “pebbles,” built up through static electricity, would clump together like a pack of racing cyclists thanks to the churn of the early solar system’s primordial disk. Those streaming pebbles would eventually gravitationally collapse into planetesimals, leading to pairs of orbiting objects that line up like MU69, McKinnon says. “That comes right out of the streaming instability model.” By Paul VoosenMar. 18, 2019 , 4:00 PM Click to view the privacy policy. Required fields are indicated by an asterisk (*) THE WOODLANDS, TEXAS—As data streamed down last month from NASA’s New Year’s flyby of MU69, the most distant planetary object ever explored (above), New Horizons mission scientists got a shock. Rather than the 35-kilometer-long space “snowman” they were expecting, angled images revealed a flatter—not fatter—version, like two lumpy pancakes smooshed together.“That took us by surprise,” said Alan Stern, the mission’s principal investigator and a planetary scientist at the Southwest Research Institute in Boulder, Colorado, today at the Lunar and Planetary Science Conference here. “We’re looking at something wild and wooly and pristine.”Scientists believe MU69’s two lobes, with their sparse impact craters and generally smooth features, are primordial planetary building blocks called planetesimals. They still don’t understand why MU69’s two lobes did not form as spheres. But their flat shapes are now the best evidence that MU69, or “Ultima Thule” as the team has nicknamed it, first formed as two small, separate objects, says William McKinnon, a New Horizons team member and planetary scientist at Washington University in St. Louis, Missouri. “This is our strongest evidence that they really did start as an orbiting pair.” The space ‘snowman’ at the edge of our solar system is actually two lumpy pancakescenter_img Email Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe Sign up for our daily newsletter Get more great content like this delivered right to you! 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