---
title: "Asteroid Flying by Earth Is so Big It Has Its Own Moon"
description: "Saturday night, a mile-wide asteroid called 1999 KW4 will fly by the Earth, and when it does, it'll bring with it its very own moon."
date: "2019-05-23"
modified: "2019-05-23"
authors:
  - name: "Kristin Houser"
    link: "https://futurism.com/authors/kristin"
url: "https://futurism.com/the-byte/asteroid-flying-earth-moon"
categories:
  - "Astronomy"
  - "Moon"
  - "Science & Energy"
  - "Space"
tags:
  - "1999 kw4"
  - "asteroid"
  - "moon"
  - "the digest"
---

# Asteroid Flying by Earth Is so Big It Has Its Own Moon

![Saturday night, a mile-wide asteroid called 1999 KW4 will fly by the Earth, and when it does, it'll bring with it its very own moon.](<https://futurism.com/wp-content/uploads/2019/05/asteroid-flying-earth-moon.png>)
*\<em\>Image: European Space Agency\</em\>*

## Buddy System

Earth will be getting not one but two visitors from space this weekend.

Astronomers expect an asteroid known as 1999 KW4 to swing by the Earth at around 7:05 p.m. ET on Saturday — and when it does, it'll bring along its very own moon.

"It's one of the closest binary flybys probably in recent history," planetary scientist Vishnu Reddy [told *NBC News*](<https://www.nbcnews.com/mach/science/mile-wide-asteroid-its-tiny-moon-zoom-past-earth-weekend-ncna1009381>). "That's what makes it a very interesting target."

## Dynamic Duo

Asteroid 1999 KW4 is 1.5 kilometers (.93 miles) wide. That's about three times the size of its moon, which clocks in at a width of about 0.5 kilometers (.3 miles).

Even at their closest, the space rocks will still be more than 3 million miles away, so don't worry about them [smashing into the Earth](<https://futurism.com/the-byte/nasas-dart-spacex-incoming-asteroids>). In fact, they won't even come close enough to see with the naked eye.

Still, the pair won't be this close to Earth again until 2036, so if you want to catch a glimpse of the dynamic duo, be sure to have your telescope ready Saturday night.

**READ MORE:** [Mile-wide asteroid and its tiny moon to zoom past Earth this weekend](<https://www.nbcnews.com/mach/science/mile-wide-asteroid-its-tiny-moon-zoom-past-earth-weekend-ncna1009381>) \[*NBC News*\]

**More on asteroids:** *[NASA Asks SpaceX to Help It Save Earth From Incoming Asteroids](<https://futurism.com/the-byte/nasas-dart-spacex-incoming-asteroids>)*

### Author social links  
[LinkedIn](<https://www.linkedin.com/in/kristinjhouser>)